What is this new feeling?

I know how you feel. It sounds to me like the two of you are close enough to talk about anything, so I think I would just talk openly with him about it. Go the the movies, have a great time, and if you're feeling it afterwards, just take him aside somewhere quiet to talk. Tell him you've always been straight, but you're starting to have some feelings for him, so if he'd like to pursue something more, then you would like to as well. Make sure you let him know that if he doesn't want a relationship with you, you are happy with just a close friendship and will pursue things like that. You want to make sure you don't drive him away if he is uncomfortable with guys hitting on him.