I have just done this exact same thing, was cutting using 400 cut Menzerna and a heavy cut pad on a DA. Perhaps the speed was too high and its left a grey ish mark which looms super shiny but still with scratches visible. The paint feels exactly the same smooth finish but its removed paint it looms lime. Tried to colour it back into the bodywork but still stayed grey. Oh well........off to the body shop 😞🙈