Most Helpful Guy
I think you are someone he thinks about from time to time. The problem is, when you think about someone you haven't seen in a long time you start to make up your own mental image of them. The mental image you make is always something you are interested in. Curiosity gets the better of him and he finally makes a move to take you out. Once he sees you in real life, you aren't the same way he imagined and unfortunately loses interest. The hug and kiss is just another way he is trying to convince himself you are the person he thinks you are. Once he has more time to think about it after the night is over, he simply feels you are not right for him.
For now, I would simply text him and say you had a wonderful time and would like to meet up again sometime, and tell him to message or call you if he wants. This puts the ball in his court.
Most Helpful Girl
just like you said yourself, ask him why