My dog growls when he has his bone

Hi everyone,

I have a 4 month old puppy and he’s been growling when we play tug of war or when he has his bones. I don’t think it’s serious bc when we play he’ll just chill after I win or after I let him win for tug of war and for the bones he’ll stop growling when I approach him when he has his bone. I think it could be from over excitement or maybe it’s his way of playing with them.

What do yall think?