I pointed this out back in November, generally, not this ebook specifically (see my link below). It seems to have started sometime last fall. BritishSeaPower, you were part of the discussion way back then so, at least then, you were aware that these changes were being made, even if you weren't aware of the extent of the changes.
Most of the changes seem positive but some are really strange, ex. newer versions of ebooks having a title page for a cover where an older version had a real cover image for a cover. The text formatting has been really cleaned up in most of them though. I can't say that I've seen any book published after 2007 that has been updated though. So far it's only pre-2007 titles.