Andrew,
I wasn't going to bring this up because I hadn't found another like it, but since you have the same thing, I will chime in. I have one PB White without the quotes around Doc, but my other PB definitely has a faint quote mark on the right side of Doc, but nothing on the left.
I would tend to lean somewhat with your theory that the typeset was initially there, but maybe to far in and made the partial strike early on, but later in the run didn't make contact with the card which resulted in the no quote.
r/
Frank
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