Hendrick is generally regarded as one of Ireland's finest young midfield prospects and only this week Kevin Kilbane was talking up the Coolock lad as a player who could even get a move to the Premier League.
Kilbane saw Hendrick first hand from his own spell on loan to Derby last season.
With so few Irishmen playing in midfield in the top flight -- only Glenn Whelan, Darron Gibson, Wes Hoolahan and James McCarthy can be considered as Premier League regulars in central midfield -- Trap will eventually be forced to turn the page and look to the Championship to bulk up the international squad, and that could lead to uncapped players like Hendrick getting the nod.
"I didn't know that Trapattoni was at our game last week, it's hard to pick one face out of a crowd of 25,000 and I only knew about it when someone told me a couple of days later," Hendrick told the Evening Herald, having scored in a 2-1 defeat for his side as Trapattoni watched last weekend as compatriots Richard Keogh, Mark O'Brien, Conor Sammon and Gary Dicker were also on view for the Irish boss.
"Even if I had known in advance that he was coming to see Derby it wouldn't have made me change my game, you can't let things like that get to you. It's not a big deal for me at the moment, I still have two years left at under-21 level and that's my focus now. But it's nice to be scoring goals and know that the Ireland manager is at least having a look.
"I got a text the other day about the squad for the under-21 game against Holland in Tallaght next month so I'm not counting on getting a place in the senior squad for the moment.
"I've enjoyed playing for the under-21s. We have a good squad and a good manager there and maybe we can push on and try to qualify for the Euros in the next campaign.
"I think for me to get into the seniors I'll need to do well with the under-21s and do well for Derby but if both of those things can happen then maybe it could come around for me, once I get some more experience."
A few years ago, Hendrick and Robbie Brady were team-mates with the St Kevin's Boys back home in Dublin and the dream was to make it at the top level in England and also play for Ireland.
Brady has reached one of those targets and is expected to win his fifth senior cap against Poland next month.
"Myself and Robbie grew up playing together, since we were eight," says Hendrick.
"Robbie is flying at the moment with the move to Hull and his run in the Irish team. Hull are doing really well in the Championship and they have a great chance of getting into the Premier League for next year.
"I'm still good mates with Robbie, we meet up a fair bit with the Irish teams and I saw him when we played Hull a while back.
"We had a good team at Kevin's. You still have myself, Robbie Brady, Cian Bolger and Eoin Wearen over in England, the rest are back in Ireland now," says Hendrick.
The midfielder had a number of offers on the table when he was leaving Ireland at the age of 16 but opted for Derby, feeling that that the Championship club offered a more reliable path to success.
"I just liked the feel of the place from the first time I came," he says.
"When you went to other clubs sometimes you were made to feel like an outsider but at Derby they made a real effort to make you feel welcome and fit in.
"I knew that if I worked hard and did well I'd get a chance to play for the first team. At somewhere like Derby if you're good enough you will get a chance," added Hendrick, who made his debut for the Rams in April 2011 and has since made 74 appearances.
He seemed to struggle for goals but he's found a scoring touch in recent weeks, with four goals in the last seven games.
"My own form is pretty good. At the start of the season I struggled with my form a bit, but the last two months have been really good for me and I just want to get stronger and better," he admits.
"I have no idea why the season started badly for me but my confidence was just really low, and now I have my confidence back and a spring in my step, my game has improved and I'm trying things again.
"I just had to dig deep, keep working hard in training until things turned for me and thankfully the season turned for me.
"It's nice to get on the scoresheet and hopefully I can keep that going.
"My target for the season was to hit double figures and I'm halfway there now, so if I can kick on in the second half of the season I might get there.
"This was a big season for me. I'm not a kid of 18 any more, I'm nearly 21 so I need to be moving on with my career, going further.
"Our aim for the season has to be to push into the playoffs and try to get Derby back into the Premier League, that's where a club of this size needs to be."