You know that windows can do that and it is from heat. I had a shower door break into tiny little cubletes like that when no one was near it. and one summer afternoon I saw my daughters car window do that. At first I heard it, then the little cubelets started falling out into her car and on the ground. When we reported it to her insurance company they acted very disbelieving, but I saw it and several other people that were visiting saw it. Crazy.