I don't remember Dany telling Grey Worm to stop if the bells were rung. It seemed like she had given him the orders as he described to Jon when killing the Lanister soldiers.
Dwight Schrute:
Why tip someone for a job I'm capable of doing myself? I can deliver food, I can drive a taxi, I can and do cut my own hair. I did, however, tip my urologist. Because I am unable to pulverize my own kidney stones.