Ok, I'm going to rock the boat in order to clarify some things. Can ball pythons be trained? Depends on your definition of trained. Can they be conditioned? Absolutely. Guys you can't have it both ways. Snakes that are conditioned to eat outside their container can become nippy right? If so you have conditioned them to eat when they come out.

I am going to maintain that if the animal is eating and shedding properly the animal is not stressed. Can loud music especially bass irritate a ball python? Yes, but not all of them care.

Should the OP have taken the snake dancing? Its her snake. If the snake is behaving normally this activity in and of itself probably did not stress the animal into death. I call bull kaka on the vet and the people that say otherwise. Most of my animals would not be bothered by this. If my youngest daughter has not stressed mine to death it is probably not going to happen. There is nothing quite like seeing your 2k animal go running full tilt down the hallway while being held by a yelling 5 year old (timeout time). My snakes end up playing house, playing snake store and watching My Little Pony. They are fine.

What the OP has done that I don't do is allow my snakes to leave the house. If I could bet on it I would say that the temps of the environment were out of the acceptable range for too long or most likely the snake just caught something. This is the same reason I think it is absolutely insane to do something like take your animal into a PetCo.