Are my dogs showing pack behavior?

This random Male Black Lab came around my neighborhood and we couldn't find his owner. When we tried to see how he acted around my Female Spaniel-Fiest Mix, Alli, my dog submitted to him. She put her tail all under her legs, rolled on her back, and licked his nose. I thought it could be for mating, but Alli is only a puppy (Born Dec. 27, 2010) and this is not mating rituals or whatever dogs do for mates. I study wolves and this seems like the type of pack behavior an Omega wolf would show towards a higher ranking wolf. I need proof of the answers also (Through science or whatever).