Don't expect much from the dealer unless you are paying for it. They will play stupid until you cave in to let them do the work.
If truly concerned change the fluid at 30K, the normal number is 60 but that may be too late on ones driven hard enough.
Quite simply, the transmissions are designed to barely make full life at best and some won't, Nissan does not care. Different heat treating on the ball bearings and some modding like on chains and other parts and the transmissions could go much longer on average, but that takes money away from the CEO (now in jail for financial irregularities). They went to CVT to begin with as they cost maybe half what standard ATX designs do.
Use the app in post #4
............it can measure the deterioration number and also reset it when needed at fluid changes, all it is is a number showing how overheated the fluid has gotten.