Okay, on your suggestion, I removed the dice from the foam but it's not really foam"rubber" like in the link. I don't know how to explain it other than just foam. I've had them in there for at least five years now and no issue whatsoever. They don't stick to the foam or sweat or anything in fact it's a very airy type of foam. I have seen dice and what happens to them also and have tended to shy away from them but every now and then, I'll see some that tickle my fancy and buy them.
Thanks for the input, Jim