From my experience, contrary to what most owners think, this is not a heat cycle problem. I see it all the time here unfortunatley. Some cleaners like tire shine, shampoo's, waxes and brake dust remover will sometimes contain a form of acid in them. When acid hits the brake calipers, they fade over time and rather quickly.

I see it in our detail department all the time.

 

My 991 C2 had that "fade" show up when it was about 3 months old (excluding the time it spent on the ship on the way from Europe to US) and about 2500 miles. No track / DE. At the time, it had only been through my hand washing 2x with no chemicals/cleaning agents applied to the wheels at all. It also went through the dealer's prep once it arrived stateside.

I took it to my local dealer and they said it is normal and they would not be able to do anything.