Do younger guys really fancy older?

I'm a middle aged married guy and rent out our spare room to students. At the moment it is a cute 22 year old guy and the other day I caught him in the bathroom wearing my worn boxers. As you may have worked out from some other posts I'm bi and it didn't take long for it to go from embarrassment to wanking and blow jobs.

But my question is is it normal for young guys like this to fancy older guys and get a kick from their work undies? Or is this guy unusual?