We also had the rear window of our 2009 Mazda 5 explode today. My wife was backing up in a parking lot when it happened. I cleaned up all of the debris and there was no sign of a rock, bb, tree limb, or other source object, so it appears to have been a stress fracture.
The car is in warranty, so I called the dealer before touching the car, but there appears to be no way that I can prove that the damage was caused by a defective window or defective installation.
My concern now is not to repeat this with a replacement window. Window replacement seems to be a great Fly-By-Night business opportunity for companies that will come out and do a quick job in the parking lot. Apparently window mounting is an important part of overall vehicle safety in terms of preventing frame crumpling, guiding proper airbag deployment and stopping ejections. I understand that it is common to place a new urethane seal over top the old, which provides for bad adhesion and increased stress on the new window because of the changed geometry. Secondly, if the old urethane seal is properly removed, apparently, the paint needs to be reprimed so rust will not develop, which will also lead to poor adhesion. There are also apparently issues regarding selection of the right urethane for a particular glass at a particular application temperature.
Should I assume that any company offering to do the job in the parking lot is not priming the metal? I would appreciate any suggestions people have.