Well, I can't say it'd definately apply to rc, but my best guess says it could...

Basically, if there's the tinyest of gaps it might not open up to the point where air can escape until the pressure inside is significantly higher than atmospheric pressure, such as when you open up the throttle.

If you're not sure what I'm getting at, lemme know and I'll try and explain it a bit better. My head's still stuck in programming world atm, damned clients keeping me away from RC