Go ahead and talk to him about it then. Age gaps like that are not all TOO uncommon nowadays. Especially when the man is a lot older than the woman. And I'm sure he's been around the block and is mature enough to seriously think about it and consider it before giving a reply. And even if the answer is "No", I'm sure he's mature enough to not let that affect the friendship you already have.

Sounds like you like the guy and get along well. Why not give it a shot? Worst case scenario, he says no, and you know that you'll have to look elsewhere. Otherwise you'll always be wondering about it whenever you talk/hang out with him.

Rod Steele