I'm inclined to believe that he just hasn't updated his MySpace...because it's such a wasteland, a lot of people haven't signed on to change their statuses lately. As for saying that he wasn't expecting it, that could mean any number of things, but doesn't necessarily imply that he has a girlfriend...could be that he was surprised he likes you that much so soon, or he wasn't looking for someone at the time.
The important thing is: do not feel bad about yourself. Even in the worst case scenario, it's not in any way, shape or form your fault. The responsibility lies on him in that situation.
It's up to you what you want to do...if you confront him, don't jump to conclusions. Have a conversation about past relationships and get some insight from there. Get solid, concrete facts and truths. I will tell you, this same thing has happened to me and I just let it go and cut him out of my life, but I sort of regret not epically bitching him out. Good luck with whatever you decide to do, Kels.