Hi all, I decided to change my strings this weekend. I usually keep about three sealed packets of Fender 00.9-.042 Nickel plated steel Bullet end on hand. I bought two packets around December 2020 and the last packet 7 months ago. On opening one of the 2020 packets I found the strings had a few black marks on them. I decided to open the other packets and they were the same. My question is have any other members had this problem and is it still okay to use them ?

Thank you John