The inside pads were wore out, the first thing I thought was that the calipers were stuck but it wasn't the case. Apparently the rotors have a hard coat on them, don't know if it's spray arced or what but moisture gets between the two layers of metal and rust starts and the outer layer starts flaking off. My buddy runs a repair shop so stopped on my way to pick up the new parts and showed them to him and he said it was a common deal, GM does the same thing. Another example of throw away parts on newer vehicles.
