Could you pick a time well before he does this next (so you're not actively irritated) and just say something like, "I really like you, and it's nice to see you more often. I'm glad you like my art and objects but I would SO appreciate it if you would look at them without handling them"? Period, that's all. I'm guessing that would do it for most folks, and it sounds like he hasn't any idea that it might be bothering you.