Farting noises coming near the gas tank

Hey guys, just topped off the oil in my 348. i don't believe this is related, but when I shut the car off I can hear what sounded like farting noises (or someone making farting noises with their mouth) near the gas tank area. I pulled off the gas cap and a lot of pressure released and the noise went away.

Is this normal or should I be concerned? I did fill up yesterday, about 3/4 tank full not to the top.

 

Okay I did a search and this is the closest I've gotten:

Your 348 Sounds as though it is "mooing" like a cow when you close the left side door?! ...it's the fuel tank pressure relief valve. They all do it, and same thing on TR family, even 360.

It's not a problem or a blocked vent or anything, the fuel tank is designed to hold a bit of pressure (generated by engine heat) to help fuel pick up and anti evaporation within the lines on hot start.

It often gets set off when you slam the door as you get out after a hot drive. The shock of the door jars the valve off it's seat.

If thats not it...it must be "an udder" problem that I can't think of......thanks, Ferrarifixer


It didn't sound like a moo but hoping this is it

 

LOL!