Just when he was finally building up a head of steam after a near seven-week enforced hiatus -- after hyper-extending his arm in the opening round of the league on September 1 -- he finally got three successive games against Welsh opponents under his belt in recent weeks.
And then, the last thing that he needed -- another break!
"Yep, while the rest of the guys had the chance to put their feet up for a few days, I was just itching to get back playing," Boss reflected with a characteristic smile ahead of tonight's inaugural visit to the new home of the Glasgow Warriors in Scotstoun.
"I was dying to get some more game time in. It's a small frustration, but look, it's a long season. A lot of the guys have done a lot of hard graft since the start of the season and they deserved a break. And I think that's the same for coaches and support staff across the teams.
"I mean, take a player like Ian Madigan who has played in 10 games already, which is a solid return at this stage of the season and there are many other guys like him in our squad which has really been stretched to the limits of late. You wouldn't begrudge the lads getting the week off, selfishly, I'm just dying to play."
Boss's frustration is understandable, but tonight he will have the opportunity to lock horns with a non-Welsh team for the first time this season. In Glasgow, though, Boss sees a side very much on the rise who have improved steadily in recent years. "Glasgow have always been tough opponents and they present a big challenge on their own turf," the Ireland international scrum-half says. That has never changed from when they played their home games in Hughenden, Firhill or now in Scotstoun.
"They have a very good squad and they have added to it recently. A few recent signings will bolster them further, which makes Friday's game a big hurdle for us because we haven't always got the result we wanted over there in the league.
"They have depth in their squad and they have more or less their strongest pack, especially the back row -- and they are a hugely physical to come up against. They contest the breakdown robustly and that has been an area which has caused us a few problems against them and something we have to be mindful of."
With the race for top-four spots gathering pace as sides chip away at each other on a weekly basis, Boss knows that the Leinster squad will need to up their domestic form starting this weekend.
"It has been a bit of a stop-start opening to the PRO12 for us, if we're honest, and we know that we have a lot more in us. To lose a few away games has obviously been a disappointment, but in saying that, sooner or later we're going to step up and really start putting away our chances.
"In a league as competitive as this one, you can't afford too many slips and with the way things are shaping up it's going to be a right old scramble to get into the play-off places.
"But this round of games offers us a fresh start with a number of new players who will be all itching to get back playing."
The journey of the wounded sportsperson is often discussed, but rarely understood unless you have the benefit of first-hand experience.
While some may not see the deep ramifications of losing a team-mate/friend from the weekly playing roster, Boss explains that it's not just the player's on-field ability which is missed.
"When you're out injured, it's without a doubt the worst part of being a professional sportsperson because it's out of your control and you just have to be patient, have trust in the medical team and work hard to try and cut down on the amount of time you're unavailable.
"That we have had so many injured players has definitely affected us. It's not an excuse that we use, but players of the calibre of Lukey Fitz (Fitzgerald), Isa (Nacewa), Seanie (O'Brien) and now Rob (Kearney) and Drico (Brian O'Driscoll) would have a major impact on any team.
"So while it has been tough training and playing without these guys, it's great that some of them -- as well as the likes of Eoin O'Malley, Dominic Ryan, Quinn Roux, Tom Denton and Aaron Dundon -- will be back in the frame over the next few weeks. Just having the guys back in amongst things gives everyone a lift.
"They're not just big players, but there are a lot of big personalities there too and they bring a real hunger and intensity, which is great for the rest of us.
"You want to see other players back and there's a great sense of personal accomplishment when you do make it.
"And for each of us it's a reminder that we should appreciate our fitness and be as determined to play as well as we can because we want to leave the squad in as strong a shape as possible for the others when they return."
For now, Boss insists that Leinster are focused on the process.
And to do this, they will take it on a step-by-step basis.
"This is probably the most competitive league there has ever been.
"We've been slowly building this year but we know that we have to up our level of performance now week on week.
"To do that we have to be clinical and consistent. That's our immediate focus."
And with those few simple words, the new challenge has been set.