Sounds like normal puppy play to me. I once fostered a kitten that my yorkie did the same thing to. I called myself rescuing the kitten by giving Duchess a periodic timeout. It turns out the kitten was initiating the roughhousing
. She didn't want to be rescued. She would run up to my Duchess and attack her (playfully)and of course this would get Duchess started and off they go. It wasn't until I actually saw the kitten do this that it dawn on me that it wasn't just Duchess, it was the kitten too who was also being ornery and wouldn't leave Duchess alone. Duchess was at least 4lbs heavier than the kitten and never her the kitten. Duchess was always trying to sit on her though.....not sure what that was all about.
As long as they are just playing and no one is getting hurt, I wouldn't worry about it. Sounds like the makings of a beautiful and long friendship.
The kitten and my Duchess ended up doing everything together even sleeping together.