Hi Joanne,
you might still think about this guy because you're emotionally attached to him. Perhaps this happens at a more subconscious level so you don't realize it at first but your thoughts always come back to him one way or another.
This can also happen because although you had a crush, there wasn't a development or something between you two, so you might be feeling like there's something that still needs to be solved or something you might wish to find out.
If you recently met him, then why not try and get to know him better? So that you can find out whether there's really something or it is just the idea you have of him that makes you feel that way. Sometimes it is just the image that we portray on somebody else that makes uf feel a certain way and not the way they really are.
You can call him and try to arrange a date, maybe going out for a coffee. I'm pretty sure you have loads to catch up on! You might find out this guy is really as nice as you thought and he might think the same way too.
Best of luck!