I have the same cracks on my sun roof. They are in 2 different places, which are 2 different pieces of glass, and they happened at different times. They are stress fractures. Now my windshield is cracking. My dealership told me that because my warranty has expired there is nothing they can do about it. This seems like a safety hazard to me and is apparently happening to many people. I'm not happy and will be adding it to the NHTSA list.