Kent has good reputation, I would email their CS with a picture of the split case.
And if you have any before and after shells I would send them all back to Kent for analysis, properly separated.
I cannot find my shotgun buddy from California bu I am thinking a bad wad, SOMETHING, in the construction process went dead wrong.
The Salton Sea area of California is below sea level and brutal cold, below zero lots of times, and none of my shells ever split. I also chased jackrabbits around Pear Valley in temps over 100 with no problems either. BTW jackrabbits do not taste good.