[JRTJH]

The "gas smell" comes from an additive to the propane. It's called mercaptin, an oily substance that smells a bit like garlic, actually, it smells like what we "consider propane to smell like". Since it's an oil based substance, it can collect on surfaces and cause them to smell like propane, even when none is present.

So, in a confined space like under the plastic propane cover, you may have some mercaptin that has soiled the plastic and is transmitting the smell. I have a distinct smell of propane in my propane compartment. Whether it's mercaptin on the regulator, on the fittings, on the tank valves or even sprayed on the door to the compartment ??? I don't know what's causing my "propane smell" but I don't have any leaks, my last manometer test of 90 minutes had no reduction of pressure, so the smell isn't from a leak.

Short answer: Having a smell of propane in a confined space doesn't mean there's an active leak. But don't ignore the smell since it may mean an active leak.