Should I bring this office gossip to my boss's attention?

I heard from a coworker that our boss and another coworker were caught in the act (if you know what I mean) on a business trip not too long ago. Personally, I believe everybody has the right to a private life because we're all adults, but I'm afraid this could turn into a scandal. Should I tell my boss about it or just ignore it? I think I'd want somebody to come straight to me if I were in his position. I'm afraid to get the person who told me in trouble, though.
There are two bosses. The one who was caught in the act is my own immediate boss. The higher up boss is his boss.
I'm not talking about going to the big boss. That would be tattling, and I would never do that.