Greg: Most of the HWH jacks have a sensor on the jack that indicate when the jack is fully retracted. If the jack moves down a small amount, about a 1/4 inch, then the sensor will close and the red led associated with that jack will light to indicate the jack is extended. If when storing the jack, the jack does not fully retract, but retracts just enough to turn the sensor off, then a small amount of movement on the jack, such as that associated with fluid expansion due to temperature change, will be sufficient to cause the sensor to open. Scary when this happens while driving, but usually not a big issue as the jack most likely moved only a tiny amount, most likely less than 1/4 inch.
This has happened to me once or twice in about 8 years. I recently learned that on my rig I am able to turn the HWH system on while driving, press the STORE button and when the light on the offending jack goes off, I then turn off the HWH and all is fine.
Roadking - Homeless, full time, wandering gypsies
Winnebago Ultimate Advantage
Harley and Honda Civic