Maybe this was old hat for others in the band, but getting the chance to perform in front of a real audience that wasn't manufactured out his friends or his father's money is a new experience for Artie. A really, really new experience that is very much like all those dreams he'd had as a kid about being some famous rock star, that he'd mostly given up on between his father's notoriety and his own mutation. He doesn't have any delusions that he's going to be some famous musician known around the world only as 'RT' or anything ridiculous like that, but the success of the concert has re-awoken at least the notion of the dream in him, and now Artie's excited, and looking forward to the idea of more concerts with this group (or some facsimile thereof).

Which would probably be why, instead of being composed and reserved or going out to see the other acts, Artie is instead bouncing around the backstage area as if he's made of flubber. He's trying not to be obnoxious about it, he really is, but there's some level of exuberance that he can't restrain in his interactions with his friends. It is, perhaps, a lot like the teenager he still was when he arrived, the teenager that he's largely grown out of being, these days. Artie, at least, is having a grand time.