The smell probably. Rabbits can pick up on our hormones quite easily. I expect also that it could be your soap, deodorant etc.. that she is smelling or doesn't like! My male bun will nip my armpits hard if I'm lying on the floor and will do the same to my OH when he's wearing body spray/deo - it can make some buns very aggressive. I think the scents used can incite aggression - musks most probably - may be perceived as a threat or another male rabbit.