10 Months 21K miles and Rear Differential Starts Leaking

Just hope the dealer can fix it in one trip and not keep my truck overnight. Also while I was under there I heard something like a small pump running, it ran for like 10 minutes, Is that normal? Truck had been shut off for over three hours.

 

The pump sound is normal, it’s an evap check. Definitely get the rear diff looked at though.

 

Thanks, I was hoping the sound was normal.