It really was the original -- I am the original owner! And thermal stress is the only explanation that I have -- it was 105 degrees, and we left the trailer all day in the RV park with the air conditioning on full blast to keep our ice chest cold, rather than taking the ice chest with us in the truck.
The temp inside the trailer when we came back was under 65, so there was a 40 degree difference between the inside of the glass and the outside. And there was the little crack in the corner of the window, which spread during the next day to cross the whole window.
