A month or so ago I messaged him on Facebook, and we exchanged a number of messages back and forth that got longer and longer (by both of us) and he shared music with me (we have similar tastes and he wanted to "educate me further') and all was going well. Then he just stopped messaging back. I didn't say anything because I didn't really ask a question in my last message and I didn't want to seem clingy/needy (especially since we're still far from the friends stage) and also because I was going to see him at a party 2 weeks later anyway.
When I saw him at the party, he did seem a little quiet at first but he was friendly and didn't ignore me. We hung out in a group and a few times he asked questions directly to me based on whatever the group's topic was at the time. (He also looked at me a lot and smiled in a way that gave me butterflies, but that's probably just me haha). He gave me a hug goodbye later that night too.
So: I have come to the conclusion that all of these interactions suggest he didn't stop messaging because he is repulsed by me (at least lol). I do know that he was going through exams during our messaging stage so that could have been a factor. Also, he has said that he is a very busy guy (not to me though) and some people I know who are friends with him say he is bad at replying to messages often. Should I attempt to contact him again? Just a casual message? Or should I just leave it up to him or let it go because it seems he's not interested in talking to me?