I just spoke with Robbie at James Marie Farms and he brought up this very thing. He said that a quail could break its back, or pull it and it would make it look like it had a hunchback, or like an emu. He said they would be in extreme pain and if I remember correctly said that they should be dispatched it that happened.
We had a quail that had a hunchback from the time it came out of the egg. It was my first hatch and I figured it would just die and it did not. She grew up and laid lovely big eggs and was healthy and happy...just had a huge hunchback and head looked out sideways. My children named her "Quailimodo" and she was over a year old when she was lost to a raccoon attack.
So maybe it is a problem if it was normal and is now like that but our one was always that way.