yep, its supposed to do that. it has to be able to move because when they fill it that pin moves back to let air in, and when its full the pressure holds it in the forward position and seals it off. only thing you might ever have to worry about is they can develop a small leak sometimes just from wear and tear. even then its still fine to use, just annoying. easy to replace though and they're about $10.
north mississippi eh? ever play at CHF?