Is This A Sign Of PVC?

Hi CCF,


Recently, I've bought a few coins from a single collection that was assembled over decades. They all come to me in the same style, brand new flips (so, they've been rehoused in brand new matching flips). I suspect PVC on some but not all of the coins.

My question: If a new flip looks like the one shown below after holding a coin in it for likely only a little while, is that a clear sign that there's PVC on the coin?

And, sorry for the photographs. It's a hard thing to capture.


Thanks,
N