Netflix knows how often I replayed the first 5 minutes of The Invisible Man, too. :) This is more concerning:

https://kindle.amazon.com/post/192I0Q7B1DRFJ

Apparently notes and highlights can be made public, with your name attached no less, and they are indexed by search engines. As soon as I saw that I rummaged through my Kindle settings (app on iPad, v 2.85) but couldn't find an option either way.