If they're sealed in nongas-permeable bags, the harm is probably limited. Heat AND oxygen are the real problem (although they are both a problem in their own right to some extent). Even if they have lost some alpha, supposedly this balances out with the rise in beta acid as alpha deteriorates. You're most likely to have lost aroma from the more volatile oils through heat, but again if the packs are sealed they should still be present to some extent (think distilling).