golden wont share toys/sticks

Question
I have a 5 month golden retriever.  He has been very sweet with no aggression so far.  In the past week he has gotten in two fights with much bigger dogs over a stick.  And then today he was playing with a dog his size and was growling the whole time they were wrestling.  He is not neutered yet.  He is in puppy training class and has always been sweet to the other puppies.  Is this just the puppy growing up or is this a real behavior problem?  

Answer
you have to watch his body language when he is fighting.if his tail is straight up in the air he thinks he is controlling the other dog and you should correct him by telling him no.if is tail is up and wagging he is just playing.ya you should probably get him neutered.
hope i helped    -Madison