Sometimes the "whooshing" noise you hear is due to a slight vacuum in the tank. The cap has both pressure and vacuum relief valves.

Lack of hearing this noise could mean the cap gasket is deteriorated. Fastlane sells it separately, and I assume you could also buy a gasket from the dealer. They are not expensive, and if a new gasket doesn't make any difference there may be a leak somewhere else in the system.

As long as you do no see liquid fuel leaking anywhere there is likely no safety hazard, but if the Evap control system is not functioning properly you could be emitting excess HC.

Many states that require emission testing test the cap for pressure holding. CA will probably also be implementing a fuel system test where they pressurize the tank at the filler neck and check for leaks.

Duke