Do you leave your stuff in the car all day or out in the garage by chance? I've seen a lot of people that do have this issue, I've also had this issues with a ball that never left my office years ago lol.
I only had this issue when using finger inserts. Since losing the inserts and only using a thumb insert no cracked bowling balls. In many cases I blame the glue. That is my theory.
Still sucks to hear.