"Yeah, I just...I like...this," Kevin failed to explain, gesturing with his chin at the kitchens, the tea, Drew, everything. He liked that even though it was someone he didn't really know too well (though he was willing to learn), in a situation that likely wouldn't arise again, he felt needed or appreciated somehow.
In the Claw dorms, that wasn't the case. Kevin didn't play Quidditch, he wasn't any good at Gobstones or chess...the only time he'd felt important was when one classmate or another would ask him to look over their essays. Writing Kevin could handle, but writing wasn't an important skill among Claws. As long as you knew what you knew, the manner of delivery of that knowledge was almost irrelevant. Kevin, of course, had taken a rather contrarian position to that: you can look smarter even than you are if you can effectively communicate.
So for someone to seek him out and ask him to be, well, him - that meant something to Kevin. He was nervous cause he didn't want to screw it up. And, obviously, because Drew's closeness was getting to him, in one fashion or another.