Hatchback/liftgate problems of the 2007 Chevrolet Trailblazer

At 7:55 a. M. On the morning of 12/10/09 in st. Paul, mn, I went out to my 2007 Chevrolet Trailblazer (approx. 18,000 miles) and opened the rear hatch (the entire door, not just the door glass) to remove a snow brush. The temperature was -5f and the windchill was reported at -20f. After removing the brush, I began to close the hatch when I heard what sounded like glass breaking. As the hatch latched closed, I noticed broken glass everywhere and the two window struts were broken away from the glass. Upon further inspection, the entire back window was broken. It was "spider-webbed" and pieces of glass were slowly separating on their own. This is the first time this has ever happened to this vehicle. Later that day, I took the car to a nearby Chevrolet dealer. I was informed that the damage was not covered under warranty. I was told that they have never seen window strut rods lock up in an extended position. They said that if they lock, it's likely to occur in the collapsed position. But one of the mechanics told me that he has seen incidents where the strut rods locked up in the extended position, but he said it wouldn't have caused the glass to break. I asked what caused the problem and nobody had an answer for me. I had the glass and struts replaced for approximately $1,100. In looking on the internet, I found several testimonials by people who had very similar incidents happen to them (I. E rear hatch glass shattering) involving GMC envoys, chevy tahoes and chevy Trailblazers. So while this may be a rare incident, it's certainly not a one-of-a-kind incident. So how many more times can I expect this to happen to me if chevy is saying it's not a design flaw and they are not at fault? if it was caused by the cold weather, it's only December and the worst temperatures in minnesota are still two months away.