Given that way the mint packing has preserved the flat pack Proof sets from the 1955 to 1964 era, that’s not unusual. The real trick is to find a cameo Proof on both sides. There was a time when the purple toning in the center of this cent would have made it a “bad penny Proof.” Tastes have changed. I will caution those who are interested in high grade, high priced modern certified coins that PCGS is where it’s at. NGC graded coins bring far less money, or at least they used to.
The older they are the more they get that way. Everything I've had graded came out of the box and into a slab holder to protect the slab from scratches. Stuff I've had graded years ago are perfectly clear. Who knows how many times these older slabs were handled at shows, in and out of cases, bought and sold, thrown around. Overall too costly (fees, shipping, reholder price) to get reholdered on it's own so this is the situation many of these coins will end up in.
With dimes it's so deep in the holder it's hard to get light in there, and then they put the coin in catawampus to really add to the pleasure.
