This is a very interesting thread...
Panasonic CR123 Explosion .
Even good quality cells can have problems. I don't think we ever figured out what happened here, except the cells got very hot.
I am aware of similar incidents occurring with all of the major brands of CR123 cells. It doesn't often happen, but when it does it is a real eye opener.
When you do a long run with a multi cell CR123 light and run the batteries all the way down and notice the light getting warm, it is always a good policy to empty the cells out of the light and let them cool off in a safe place. If the batteries decide to misbehave, at least they are out of the light and in a safer place than in your pockets.