When they lock onto each other they either grab each other and lie on their sides and start kicking, or they lock teeth and whirl around .I think it sounds like he'd just had enough of her showing him who was boss. Mine have a little spat occasionally and there are little chunks of fur. She might just have been a bit out of breath afterwards and sulking. It is worrying I know but it's to be expected when two rabbits (or people!) live together 24 hours a day.