i went to the dealer today about the problem. The service manager explained to me it is a rare occurence but it has happened before. Apparently the Gromit? (dont know if that is spelled right) that is in place for the rear window wiper is not placed properly or not even there on some cars from assembly. With the rear defrost. the temp flucuation. science takes its course.

 

Sorry to hear that man. Hope you get it straightened out though.

 

Meh no worries dood I think everything else would account for stress on the window tho...

 

Here's a science experiment for you:

Run a regular drinking glass through the dishwasher on the hot cycle.

Pull it out immedately when done.

Fill up the glass with cold water from the facuet.

If the correct conditions exist the glass will shatter.

Similar situation could have happened to your rear window... but who knows for sure?