If you check on average every three years, the odds of you checking the very same day the book comes out are about 1‰, which is improbable but not _extremely_. Add that together with all the probabilities of things that would make you think "wow, that's improbable" and we have pretty high odds of something improbable happening.

I'm sad my second thought about this (after dismissing it as a coincidence) was that it could be used for marketing - "I randomly thought about this book/show/movie whatever, and hey what do you know? The sequel is coming out!". Basically another variation on 'organic' advertising in comments that's been around for a while.

Of course I highly doubt that's what actually happening here, but the idea is unpleasant. I hate advertising, I don't want it messing with real interactions with other humans. I'm not sure how to express the idea, it's like its so pervasive I'm thinking about it when its not even present.

Is it possible this is due to a memorability bias, where perhaps you’ve done basically the same sort of thing many times before and just forgot about it because nothing noteworthy happened? Then it wouldn’t be as much of a coincidence.