We never discussed it before.
If I am in the mood and he is not, I will place his hands on my chest. He will lick my nipples and play with my breasts while I masturbate in order to help me get off. So, I would say he doesn't mind.
He has never touched himself around me unless I asked him to. When we were not together, and we were being intimate over the phone or online, then I'm sure he did. But in bed together, he hasn't done it. So, if he is in the mood and I'm not, then I will masturbate him. If he chose to touch himself, I wouldn't mind at all.
We are comfortable together, and I think that proves it.