Call or write the manufacturer. I had a box of bird shot that had 2 FTF when the primer was struck. Absolutely my fault for storing the ammo in a humid basement. ~3-4 months old.
I told them about it anyway and they sent me an airbill because they wanted the ammo and the cardboard box for the manufacture batch number back for testing. They sent me a couple of coupons for 6 boxes of ammo free for my troubles.