LP cut off with full tanks

[SummitPond]

We left our Maine outpost a week ago (and we're still not home yet); while traveling we run the fridge runs on LP (Dometic 8 cubic foot). No problems until the other day when the check light came on. We cycle the power switch and it goes off but then illuminates later when the fridge tries to chill. I check the cook top to see if there is any gas; nope! I check the regulator and it shows red. I didn't have the other tank open as I didn't think I was low, so it didn't automatically switch. I open the tank SLOWLY and change the regulator to select the new tank. The window stays red. I disconnect the hose from the tank and it makes a "pfft" noise, indicating there is gas. So I loosen the tank hold-down and remove the tank. It turns out both are full (or nearly so). I tip them sideways an stand them back up, put them in their rack, tie them back down, hook up the line and voila! Gas. I confirmed the fridge was running by listening for the pilot - a nice sound.

Any idea what happened? Is it possible for the anti-tip device to trigger while one is traveling down the highway?

Thanks again for your insights.

[chuckster57]

No pilot light, it’s either on (flame) or off (no flame) based on interior temp.

No idea why it did what it did.