Sounds to me like he might be trying to hint that he'd like to explore a little more, that's all. It doesn't have to mean anything negative about you. I'll bet there's something he wants to try and he's working up the nerve to ask. Why don't you help him out and see if you can gently get him to tell you? Maybe you could take the pressure off by incorperating it into some sort of game, like a truth or dare, or "tell your fantasy" sort of thing. It might be fun!
