Very rare for a damsel. Not saying necessarily your situation, but sometimes the fish we buy might physically look OK, but mentally are damaged goods.
I think cyanide collection or just normal retardation can sometimes be the culprit. We should assume that a percentage of the fish population, just as the human one, is going to be mentally disabled. I would also assume that these fish are probably more easily caught. Anyway, this might not be your situation, but damsels are usully voracious, and made me think about an oddball I once bought! Good luck with him