A Quick Hookup That Turned into More Than I Expected

So, this happened a few weeks ago. I was at a friend's party and ended up with someone I barely knew. Nothing too intense, just some quick sex in the back of an abandoned car. It wasn't like it meant anything, it never does. Or so I thought. Fast forward to today: turns out this girl from the car, Emily, moved into my building last week. We bump into each other sometimes and she'll shoot me a wink or something equally as awkward. Last night we even had dinner together, just casual conversation and that’s it, right? But then, after dessert, her hand found its way to mine under the table. So here's my question: is it normal for a one-night stand to become more than just sex? I mean, I'm not sure if there was any real attraction at first. And now I'm second-guessing myself, maybe that whole car thing meant something deeper back then and I’m missing some kind of sign. Thoughts?