Passing gas?

Pure and simple: BS

I have a travel trailer and always travel with the gas on.  

first all with the new style valves on propain tanks if there is a large release the tank valves shut off, so there is no advantage to having it shut off while you travel anymore, maybe with the tanks of old but they have been outlawed for over , dan how long has it been, 20 years I dare say as I have tanks that are 5 years over their 10 year life that have the new style.. somthing like that anyways.  

there probably has been a fridge fire or two, could be stationary or moving for all we know.. that would be from pour maintenance or a defect rather than anything else in my opinion. 

Mine are always open when traveling, I also run my refrigerator on propane while traveling as it is the most efficient and coldest.  

I always travel with propane on and the refrigerator running.
Does it have a built in propane tank or is it a remove to fill tank? If remove to fill if it has a triangle or 3 lobe handle it's a new style tank and has a large leak the valve will shut it off.
A fridge fire happens when the system overheats and ignites the wood behind the refrigerator. I would say you are less likely to have  a fridge fire while driving down the road because there is more airflow to cool things down.
In summary, it's a non issue wives tale.