I've had that happen as well a few times. Grafted queen cells, the cells take. They are long and look normal. I dispose of any that are too long, too short , or not quite right looking. I pull them and put them in protective cages for emerging. I come back a week later and there's a worker bee in one of the cells. No way for it to get in there accidentally and the queen cell is opened properly. I've also had them unable to get out of the queen cells and die. Rarely when I open the cell there's a dead worker. No doubt they were dead workers. Even a dried out dead queen still has a longer abdomen with the ring and peaked crown on the thorax.