Yeah I know but what about in 2-wheel drive after leaving the car locked in a locked garage?

Mine comes on and off at random about once or twice a month. I'll drive to the mall, park, and come out and the lights are both lit and won't go out. The indicator (and butt dyno) say that the truck is in 2-wheel drive. Stopping and starting the truck has no effect and neither does actually putting the truck in 4WD and locking and unlocking the diff ... and the weather is so dry I don't think the truck has been wet once since I bought it in September when I crossed the Mojave road.

I've bought a ScanGaugeII to see if it's throwning codes that disappear by the time I get it to the dealer but last time it happened - no codes.

The first couple of times it happened I was worried. Same with the first couple of times it got stuck in 4WD low. Trying to drive faster than 25 mph on pavement ain't possible when stuck like that which makes it a real concern.