White Rogers 9600 Thermostat-Set at 70 Deg,dropped to 62 deg-no heat-Trane XR90 gas furnace
There is default programming that somehow probably started running. Maybe somebody pressed &quot;run schedule&quot; or &quot;use schedule&quot; or &quot;run program&quot;. If you set the t-stat to &quot;permanent hold&quot; and it still runs the schedule, it's probably a problem with the t-stat itself.
Found this nugget in the install manual for your t-stat. What intrigued me is the default of 62 degrees is what you were experiencing.   The times might be off, install manuals aren't always fully accurate.   EDIT:  just noticed the comment at the bottom of the snippet. 6:00 AM!  Sounds like the default program started running.