As long as its stats upgrade its not ninja looting, now mage rolling on attack power would be considered as nl, but you cant stop mage from rolling in dungeon on something that gives him more spell power.
As for the reason to get banned, there are a lot of holes in the rules that can be unclear, I myself got banned and unbanned for ninja looting. If you think you re innocent and didnt do anything wrong, ask for a ban appeal, but please be 100% sure of it and be ready to prove it, otherwise dont waste their time.