PVC or not PVC? That is the question.

This wasn't exactly a shining moment for me in coin photography. In
fact, I was blowing off a couple of shots of film using a very odd
combination of equipment. (Nikon F100, Ektar 100, a Pentax(!) 120mm
f/4 Macro, and a pair of supposedly daylight balanced fluorescents).
As a result, the color balance of these shots is a bit off:

http://wemightneedthat.biz/Coins/1853obv.jpg
http://wemightneedthat.biz/Coins/1853rev.jpg

That said, what about those spots on the back of this half-cent?
On the coin, they appear to just be dark spots, but on this
particularly shot, they look an awful lot like PVC. The coin is
currently housed in an old green label PCGS holder.

What says the jury?

--
Mike Benveniste -- (Clarification Required)
Its name is Public opinion. It is held in reverence. It settles
everything. Some think it is the voice of God. -- Mark Twain