I think all puppies do this. It's important for the owner to correct this behavior immediately. Mine would do this all the time but but after a quick jolt on his lead while he has his corrective collar on he has stopped doing it for the most part.
Mine walks around ripping roots out of the ground and branches off of small trees. For my GSD, it seems like a frustration thing- he mainly does it if it's been a busy day and I haven't walked him as frequently as usual. I swear he does it to get a reaction.