GX 460 Buring rubber smell

Just drove my new 2016 GX 460 that i just bought from a dealership with 30K miles up a ski resort mountain and smelt buring rubber smell emitting from the car, what did I do? Was I supposed to have it in 4AWD low?

I was driving pretty slow because of the fog, nothing seemed out of the ordinary, no high revs or weird shifting.

I used engine breaking on the way down and didn't smell anything, only smelt something on the way up