No, it doesn't, and it's a silly question to ask. It has no meaning. There's no way to prove that something is "unread", by any means. For a slabbed book, it's completely irrelevant. It could have been red 10,000 times, and still been a 9.8. It could have been red zero times, and been a 6.5.
Yes, I understand that "read or unread" actually means "was this book handled, and does it therefore have handling damage", and it's a fairly legitimate question to ask for raw books...but the slab and grade put that issue to rest.
I wouldn't have cancelled his bids, but I would have carefully considered blocking him.
OCD is fine, when it is contained, and doesn't spill over into asking silly, unprovable questions. We ought not cater to such behavior, regardless of the "affliction" the person asking may have.