The sunroof in my wife's 2012 Subaru XV seemingly exploded outward without any obvious reason as she was driving to work. She managed to get some photos of the glass appearing to erupt from the inside out; clearly showing nothing has externally been forced through it. Subaru insist that as this is glass related, it's not covered by warranty. Are you aware of any other instances where this has occurred? What are the possible causes of spontaneous glass explosion? Surely this is a product failure and as such should be covered by warranty?
Glass is not something that is normally covered by the warranty, but the problem your wife has experienced is not normal. I would expect it's a design or quality issue, a product failure as you say, and should be fixed under the warranty. Go back to the dealer and have them take photos of it and send them to Subaru with the request to have it repaired under warranty.