He's a great catch, except... What would you do?

He's a great catch, except….. he picks his nose! Ok, I've been dating this guy for 3 months now and everything is going great except that he has the (very gross) habit of picking his nose in front of me. Well, not directly in front of me, but sometimes when I'm at his house or vice versa and I'm in the kitchen, I'll see him picking away. Or, at the movie theater the other night, I could tell out of the corner of my eye that he was picking and wiping under the seat (Gross!) My sister and my mother have seen him do it, too ….. Usually, I just say "hey, caught ya", and mimic the behavior and just chuckle a bit, but he doesn’t seem too embarred. He's a great guy, and I'm not about to break it off yet over a little nose picking, but at the same time I'm not sure I'm ready to settle down with "Booger" and I'm not sure how to broach this with him. Thoughts?