dog reactions to new puppy

Question
hi- we have a neutered 5 yr.old chow-lab mix who we have had since he was a puppy, recently got a new male puppy-pug/boston terrier(2 weeks ago) unsure if this is just normal play behavior, or something we should be concerned about. our dog will "nose" the puppy over and over again, puppy doesnt run away, just lays on floor belly up, when dog stops, puppy runs at him, earlier our dog kept mouthing him, we actually thought for a minute he was biting him, but then realized only spit all over puppy, and no cries from puppy. is there anything we should be concerned about/look for. dog ocassionally growls at pup but no teeth/no snapping, more like get away from me and or my food

Answer
Your older dog appears to be demonstrating normal adult dog behavior toward your new puppy; if the puppy were being hurt or frightened, the puppy would show it (by running away and attempting to avoid the adult dog.)  It is normal for an adult dog to mouth a puppy, sniff and prod a puppy, etc., and even growl at a puppy (as fair warning.)  So far, so good.  Treat the adult dog in the same way you always have; show the adult dog the same amount of attention; feed him first, pet him first, acknowledge him first (to demonstrate to both him and the puppy that he is "in charge" between THEM, not over you).  So long as the adult dog is behaving appropriately and not in any way hurting (or attempting to hurt) the puppy, you're okay.