I think KDP Support is being, um, disingenuous in saying this not a new feature. I read a lot of books on my Fire HD (a 7-inch tablet, I believe) and I never saw it before reading The Secret Knowledge. What makes autohyphenation especially weird in this case is that the book is formatted ragged right! So there's no need to break words at all.
(And yes, Hitch, I see this on the Fire HD, so it's not limited to the 6-inch tablet. It doesn't however seem to affect any of my books, including those updated and republished within the past month.)
I reported The Secret Knowledge for the formatting problem, as someone on the KDP forum suggested.
The Secret Knowledge: On the Dismantling of American Culture by David Mamet
Link:
http://amzn.com/B004IYIU0Q