Jen, this is some merit to what he said but the main thing is that his back was probably on the way out and this just sped it up some.
Its like when someone says that they got out of bed or sneezed and their back went out, i know everyone is familiar with a story like that, but the hard truth is that it was just the final straw that broke the camels back, pardon the pun, but it was on the way out before the sneeze or waking up.
Back trouble can manifest it from many things, including stress and i keep preaching that tight legs are the main culprit 99% of the time.
After i play pool for 3-4 hours, i go to do my stretch , which i have done before i played, and when i do it after im done, you wouldnt believe how tight my hammys are. The stretch disipates the tightness instantly and my back feels it instantly.
The very sad thing is people are too lazy to do the work to keep their back in shape and avoid all this trouble. They rather keep all the chiropractors in business.
So be it.