Hmmm, if you were in very high heat, if the sun was shining on that side, almost directly on that window, that could be the reason. But, it would seem to me, that it would have shattered in to hundreds of pieces.
We went from Yuma, AZ to Mesquite, NV to visit friends. Part of that trip was CA-95, and that one trip cured the BH of ever wanting to visit CA again, or even live there. We got stuck in Road Construction for 2 hours plus, and then they would not ever let our north bound traffic go, and only let the south bound traffic go, plus the road was so rough I thought the coach was going to vibrate apart. LA used to have bad roads, now CA has the worst, guess you get what you pay for, a trail costing 88 billion dollars which goes to nowhere.