Gas Furnace Issue: With this I keep the gas burner and the blower as separate components.
My gas burner will usually shut off before the blower, but a couple of times in the last three days it has not. I will hear the blower shut off and the burner will remain on. As far as I know the burner would remain on indefinitely, but I can kill it (as for why it works is beyond me). I flip the blower switch from "Auto" to "On" and the burner turns off.

I had a furnace guy check it out two days ago and he could not replicate the problem. He suggested I change my thermostat batteries (and I did then and it happened again this morning).

Additional Details...the blower is shutting off when the temperature of the house meets the thermostat setting, as it normally would. However, the burner is staying on. When I flip the blower switch from "Auto" to "On" I think I hear a relay engage/disengage. I always flip the switch back to "Auto". It is fine for essentially the rest of the day after that.

I've only had the problem twice. Both times it was in the morning after the first "run" of the furnace for the day. We use a programmable thermostat and set is back at night to 65. At 5am it is set to go to 69. That is the only time there has been a problem.