He probably feels like he has a reputation to live up to. And old habits die hard, very hard.

*looks down, looks back up at her* Guys learn about the world from their dads, and if they don't have dads from the closest thing they have to a father. His father was probably very proper, told him about the right way and the wrong way to do things, and he still believes in that. And if it's special to him to do or be something, he'll try and do it, be it in the right way. Even if it's not the way you're used to.