We prefer to think that these spots were on the coin in a latent state before grading OR more likely from moisture in the air hose when the coin and slab parts are being blown-out during assembly of the slab. This problem was turning up at all the TPGS. I'm pretty sure that PCGS was the first to void guarantees for the grade of SE do to spots. The other TPGS followed.
Now seeing the entire holder, yes, I'd guess PVC residue. Sadly, you should get it conserved, as it might be damaged now, but it's only going to get worse.
PVC is simple to remove yourself at this stage. Acetone soak should take it right off. But then you lose the rattler. But you save the coin...
I honestly don't know about mine. Being that it's 2016 I don't see that it's post slab. Either way it's a bad deal, send it back for a lower grade. I wouldn't waste the time. Thankfully I have several some are PF70 and that this is the only one affected. My main purpose in sharing was to show the OP that sometimes things show up on coins post grade and slab.
I know previously when ive done anything spray paint related with air,that they have moisture filters and catches in place so there isn't moisture going through the lines,and into the guns etc. I betca PCGS has some kind of moisture filtering system in the compressed air they shoot so they can avoid these types of problems all together.
They do have filters and dryers but there can still be condensation in the air lines. Air gets hot when you first compress it. The trick is to cool the air before it reaches the air lines. Don't think you can have air that's 100% moisture free.
OF COURSE THEY DO. At least one on the main compressor and one on each line to the work station! The ones I have seen still blow a visible haze you can see on occasion when held against the proper background. Perhaps someone has been inside PCGS to check my post.
I agree, and if what I remembered from chemistry many many moons ago. By the way I failed chemistry big time. But I do remember something about air has moisture but certain gases do not. That's like in the bag of potato chips, that's not air it's a certain type of gas. Like I said I failed chemistry so I can't remember what type it is.