The air bag shouldn't be left in that postion for too long because over the life of the bag it's inflated to basically one shape. when it's deflated it's in a different shape.
As the bag ages, the rubber gets hard and inflexible. When the bag is resting in it's new shape for an extended period of time, it could lead to cracking...

EDIT: you Can replace just the air bag on the front strut but it's a PITA and if there is any fluid leakage in the strut itself then that would need to be replaced anyway. It's better to just replace the whole strut from Arnott. It comes with a really good warranty.