Yes, you know my carbon monoxide alarm did go off back in December, while I was out of the house, for an unexplained reason. I assumed it was due to my charging up a boat battery that I had forgot to remove from the battery charger, and had been charging for like 12 hours which is way too long.
Once, using MinWax wood stain inside the house also set off the carbon monoxide alarm. Another time, lawn mower exhaust fumes blowing in through an open window set it off.
Propane is stored in the tank as a liquid, and changes to a gas at the regulator before it is used by the Rinnai heater. For safety purposes, I think propane should be considered to be very similar to gasoline, a volatile and explosive liquid or gas.
