You shouldn't have any trouble if you're just going to the university library; they shouldn't even check. There are plenty of middle-aged people in college, so you'll probably blend in just fine (unless you really ARE a floating head in real life).
If you use the computers, you'll probably need ID, though some places are probably lax on enforcement.
Yeah, sorry, I know I'm not boorite. If it's any consolation, I'm in my boxers right now.