Would this be a weird thing to do? Straightforward answers preferably from guys?

Go ahead and add him on facebook. He will remember you if he likes you and accept the invitation. If he doesn't then you know he doesn't like you. However, he might ask how you found him on facebook. Simply say the facebook suggested you "might know him" on that one little tool bar thingy. Anyway, good luck and definitely add him on facebook :D