I haven't had the problem you describe with the electric thermostat, but I do have a problem with the propane thermostat. It doesn't keep the water as hot as it should, but only occasionally. Sometimes it doesn't allow the heater to heat at all. I simple off/on on the switch turns it back on.
I do have a replacement thermostat, but haven't installed it yet. That may be today's project since the water wasn't hot this morning.
2006 GMC 2500HD CCSB 4x4 Duramax/Allison, Titan 52 gallon fuel tank, Prodigy Controller, B&W Companion Hitch
2010 Jayco Designer 35RLTS, Cummins/Onan RV QG 5500 EVAP, Progressive Industries EMS-PT50C, TST Systems 507 TPMS, RV Flex Armor Roof