Is my male coworker acting strange?

I am trying to think that he is just naturally nice, perhaps clumsy, and I have trouble making out his words sometimes. He just seems to act a little odd around me, and it kind of makes me feel slightly uncomfortable at times from his body language. I don't know why, but my instinct is telling me that he might like me, except I really cannot see any reason why he would. Maybe I have read too many of those "signs that a guys likes you" articles, but even when we were sitting next to each other while he showed me something, his knee slightly touched my knee and I didn't feel him moving his leg back (partly because I retracted out of reflex to notice), or maybe it was really by accident? I am new to the place so I've been trying to get everyone's phone numbers. With my other coworkers, exchanging numbers was no problem. But when I asked for his, he only gave me his and did not ask for mine. I'm confused. What is going on?