It would. The chemicals inside are designed to be reactive, both the primer and the powder, and they will react slowly if left to sit, just like photographic film that you should store in the fridge. Dynamite becomes unstable when it ages, and many modern powders have the same active ingredients. If someone hands me a box of old 45 ACP ammo, I will remove the bullet [sometimes it is welded in place due to corrosion, so it takes quite a bit of force to free], dump the powder, carefully remove the primer [which may be inert, but maybe not], clean the casing, and reload as usual. Look for signs of corrosion on the cartridge.