New smaller dog jumping and play biting at bigger dog

Hi! We recently brought home Shelby- a 2 yr. old female Hound?mix. Our 2 yr. old male Akita/Collie mix (Blitz) has really taken to her. The only problem we are having is the fact that Shelby likes to bite at Blitz's neck and jumps alot. Blitz doesn't seem to mind and returns the favor. It always starts with Shelby being the instigator, they play bite and jump on eachother and when we tell them no, they start licking eachother's lips. Are they just playing or is this a challenge of dominance? They were both strays from the pound and are both fixed.
Any advice?

Just sounds like happy dog play to me.

:D