Well........
You have a gas valve on water heater, a gas valve on fridge, a gas valve on furnace, a gas valve on stove/oven, numerous fittings/connections........all of them can leak.
It's not uncommon to have to 'purge' the propane system after tank/cylinders have been valved out for a while.
It only has roughly 0.4 psi in system (11"WC). Not a lot of pressure.
In every rv I've owned....I've lit off stove top burners first after valving in propane. To get propane flowing and to place demand on regulator.
This helps when lighting off furnace, water heater, fridge
Some folks call it purging/getting the air out...I prefer establishing flow/demand.
0.4# dropping to Zero a couple days or more after propane valved out......personally I would not be concerned or waste my time hunting for the 'leak'