I think it might have been net graded for an old cleaning. This might also explain why it's STILL in a rattler holder. Because it might no grade today. I'd leave it right where it is at.
Agreed as well, and if you try to get it regraded i think at the very least it will come back with a label that says "cleaned" and will probably push most buyers away. And will have people offer the 35 or 40 grade prices... But still not a bad coin considering the date, and the fact that it's in a PCGS slab! Do you care to disclose what you paid for it?