Some mint worker used his finger to press an improperly seated cent into the holder. It happened. The set hasn't been tampered with. Surprise, not every coin in a proof set is perfect. And back then I don't believe you could return/exchange sets.
If you don't like the set, and you can, send the set back to the seller.
If you don't like the set, and you can, send the set back to the seller.





















