Mike,
IMHO (and I'm no expert on windshields) it sure looks like what you surmised, either a body twist or a temperature driven warpage. If you leveled the coach after install, this could be the cause. Sitting in the sun in FL could drive the interior temps up. If there was a sudden cool-down in the evening, warpage could occur. That said, an improper install could also be the cause. Consider contacting the installer. I don't think adding urethane would be a problem as it stays flexible but it would be better to find the cause as this will probably get worse when the coach is driven and repeatedly leveled/unleveled, etc.
Steve