I bounced off her books pretty quickly. For a world in which time travel existed there was way too much "Gee, you just missed him" or "Oh, she just left". I got annoyed with that pretty quickly and never really gave the book a chance.

Not everyone reads the same books at the same time. It was a good book that people enjoy reading so they want to share the excitement when they finish it. It's definitely not astroturfing. I just got around to reading it a couple months ago. I thought about making a post but held off. Then a few days later someone else put one up. It's a totally natural pattern for books to spread by word of mouth like that.