This is too confusing, some insight please?

I have been hanging out with a guy for the last few weeks, usually on the weekends when we're both drinking in a social setting, so finally last night he asked me to go over to hang out. It was fun, we got along he was attentive and affectionate and flirty, and a little shy.Then after we slept together (which I initiated) he acted weird and distant I kind of I got a weird vibe, I had to leave soon after because it was late and I had to work early. He gave me a kiss and walked me to my car, but somethign just felt off. What do you think? It wasn't the first time we slept together either.