..........I hope this hasn't been addressed in a prior thread, so forgive me if it has.

I have a 2020 TRD pro that I've put 11,350 miles on in just over a year.

A few days ago I reversed the truck down my driveway staying on the incline, and then put it back into 'drive' to go up the drive at a very slow speed. When I did so, the slip indicator light went on and I heard that grinding noise for just a second or two.
I took the truck into the dealership on Saturday and they looked at it over the weekend and today. They checked it out thoroughly and told me they couldn't find anything wrong.
They checked the VSC system, TRAC system, active traction control, hill start assist control system, etc: NO issues with any of them. They reassured me of this.

I haven't done any significant off roading yet-- in fact my first venture was set for next month.

Their diagnosis was that the rear tires simply are losing traction for that brief second going back up hill after the car has been reversed downhill, although the stock Nitto's still seem to have good tread.
Has anyone else dealt with this and are there any thoughts as to the cause (i.e. is this simply my rear tires starting to lose traction at 11.5k miles?). Do I need to be concerned and take it to another Toyota dealership?

Other this new issue, the truck has been amazing and running great and I've put several long trips on it.