Regards Mathew Napoli: "is there something wrong?"

How many miles on your Z? You might check for lash in the drive train. Worn universals or wear in the differential are suspect.

Raise your Z from the rear lift point & apply all safety precautions. With the car in neutral, as forcibly as possible rotate a rear wheel back & forth. If you suspect excessive play then check the driveshaft universals. Nissan will tell you the universals cannot be replaced, they can.