If he's eating, drinking, peeing, pooping, and active - he's doing normal chin things and is fine. If you just got him and his poo is loose, it could be the stress of the move. dump the Petsmart pellets, get some good quality hay, and get him some good pellets. He can live on hay for a little bit and it may help clear up the loose poos. Also, if he's already having issues with poop, then Mazuri may not be the best choice. Many people, myself included, have had Mazuri cause loose poos in their chins. See if the store carries Oxbow instead.
We can't tell you how to fix the poo problem for good because we don't know what's causing it. If it's stress, it should settle down. If it's food, it should be better with a better quality pellet. Try using water filtered for giardia or rerverse osmosis water - that may help as well. There are just too many variables to be able to give you a quick fix on this.
Pull the pellets, give better hay and water, get better pellets. If they poos don't clear up in a few days, take a stool sample to the vet and have it tested.