Well, there are worse problems
Let's imagine you have some "sending out unavailable, not interested, friend-only circuitry" you use in social situations.
Before, you were on "low power."
Now that you're in college, on campus, and socializing, hanging out more than once, etc. - > MAXIMUM POWER
You may find some tactful ways to, once you meet people and get friendly with them, to let them clearly know you're in a relationship AND are strictly interested in female only relationships, but cool to hang out, etc. No one will be overly offended if you make it really clear, it won't mean a thing. But apparently the missed signal is a lot riskier.
Remember too that guys, especially at first, have no brains. You can say "I'm gay", and they hear "I'm confused and would like to explore life with you". So it has to be a few times, and very clear. After that, should be OK. Just don't let it hinder your potential future friendships with straight guys!
*edit: Keep in mind, he could have been a creep, but he could also have been innocently smitten. And while it's not OK to kiss someone without some signaling, if he was infatuated with you, his adrenaline could have been going, and it literally makes you a bit crazy. While you were just friends, in his mind you may have been "the one" (or anywhere in between). Maybe he missed some chances in high school, and felt like he was way too slow, and vowed to never "miss a chance" again, and be more forward, etc. He's learning too at that age and in that pressure cooker of early college years (I assume). There will be creeps too, but I think a little forgiveness and re-adjusting is in order. That said, if he creeps you out, no harm no foul, move on.