Late Night Decisions

I've been dating a couple of guys casually but nothing serious or exclusive. Last night after work at the bar, I ran into one of them, let's call him Tom, who stopped by for drinks. We chatted about everything under the moon and somehow ended up back at my place for some late-night coffee. Before I knew it, we were getting a little too cozy for just friendly talk. I was surprised by how quickly things heated up, but also kind of turned on by the spontaneity of it all. Afterward, I felt this weird mix of relief and guilt; it wasn't that I regretted anything, more like I'm not sure if it should have happened at all. Was it just because we were both tired after a long day? Or is there something deeper going on here with Tom that I haven't acknowledged yet? Should I tell him about how I feel or let things play out naturally as they have been so far? Any advice would be appreciated, I need to know if this sort of thing makes me some kind of commitment-phobic flirt, or just a normal person who has fun.