Welcome Hot Secretary
It certainly could be that he is interested.
the age difference ~ if you don't mind me asking?
Could it be a factor?
Are you certain that he isn't married, by the way?
If he is a free agent, and you will be working with him a lot, then I see no reason not to ask him if he'd like to go with you for lunch somewhere. I have been for lunch with male colleagues on a friends basis, so, if he is not feeling romantically-inclined, after all, there would be no need for embarrassment.