How could this happen?
Easy....just like all the rest of the cheap Chinese crap that is in our campers, the same holds true for the glass they use. I am a glass artist and have a lifetime of experience with kiln fired glass. The glass most of these companies use is simply scrap glass of different kinds from multiple sources. All glass has what is termed a "coefficient of expansion". Simply put, different glass expands and contracts at different rates when being fired in a kiln. If you don't work with a batch of glass that all has the same COE, stress will be left in the final product. This stress will eventually result in the glass "popping" (fracturing). It doesn't matter whether you jostle the glass or keep it absolutely immobile. At a microscopic level the glass is moving along the stress lines....think of it as a mini San Andeas fault line....and sooner or later the piece will shatter. It's not your fault or anything that you did or didn't do....the blame lies with these companies that use inferior materials and processes. It's the glass equivalent of those China Bomb tires. The RV industry needs to take a good hard look at itself....and we as consumers need to start educating ourselves and demand higher quality.
2017Winnebago 2500RL, Hobie Odyssey
5.7L HEMI V8, Tekonsha P3
Blue Ox 1500
WDH with Sway Control
DW & a feisty Border Terrier named Painter