Dude, I'm the same, in fact the band is.I also rarely socialize at gigs. I tend to set up, and if I can, I just sit behind the kit and play on my practice pad. This is more the introvert in me. I just can't bring my self to hold pointless conversation with drunk people.
Doing the functions stuff, plastering the fake smile on to play Brown Eyed Girl and Sweet Home Alabama takes a lot out of me!
I also sigh when a conversation starts with "Hey are you the drummer!"