Growling while playing? Is it normal/ok?

So my pup Dolce, plays ruff with our 11 week old chihu. Dolce is 7 weeks, today. Ivy is a lil rough with her, but they get along fine. When they play, Dolce growls, but neither of them yelp, as if theyre in pain. Also, they will sometimes lay next to each other, and wrestle untill they both fall asleep. This is my first pitbull, and my family doesnt really like the growling. My aunt when she was younger, had a dob and a poodle, and when they came home one day, there was no more poodle. I told them, the two pups, are just playing, but you know the rap pits have. what do you all think? heres a video, of how they play. Notice at the end, dolce gets tired of it.