Mine will groom each other, and groom the willing kitties, and the willing kitties...even the males...will groom each other and the Yorkies. It can be quite the licky kissy love fest here. In fact, so much so that I took video of Mia and Smokey, our long haired black male kitty...they really get into the grooming bit and when she gets done, he is a very 'spitty kitty'.
In my experience with cats and dogs, the behavior is natural and loving between them...and definitely preferable to aggression or fighting.
