, I've noticed this too. *B/B is quite common but still attracting more money than the book would say. It used to be listed at $30 years ago, which is about what it's worth today.
Perhaps a large number on the market temporarily drove down prices. Or the huge gap in prices between some of the rarer replacements and the more common ones just got unsustainably large?
IMO:
I think people are waking up to the fact that any replacement in higher grades is a desirable note to collect. Common notes are going down because they're traded all the time online. We see so many they've lost their lustre/attraction, while the asterisk replacement (something no longer made) will always rise in value, and are so uncommon in comparison to the regular issue.
I would say the book is behind most of the 1954 replacements: even the lowly *B/M with the recent no FPN variation, and 67 replacements, are all earning a lot more respect/attention of the collecting community. I still maintain that the book is behind in the uncommon signature combinations/asterisks (Beattie/Coyne and Bouey/Rasminsky) and the lower numbered issued notes, but we have seen adjustments when it comes to such rarities as the *N/Y $1, *A/B $2 * I/X $5, and some of the * $5, $10, $20.