Test your pack at the beginning of the season and you'll never have that issue.
Besides that, the materials that they make the bag out of are very high grade and are not going to deteriorate like some grocery store plastic bag.. They are made of the same grade of material that they build high end inflatable boats with. That's pretty much a requirement, otherwise the bag risks bursting under the amount of pressure that it receives and any sort of recall associated with such a problem would absolutely kill a company's credibility in the market.. so they're all, if anything, overbuilt and made to last. That's why you spend nearly a grand on these things.
If you pull your cord and see that the bag is showing that sort of deterioration in even 25 years i'd be surprised unless you stored it in a really really shitty way.