The Amazon store page for my ebooks has just been updated to reflect changes in the covers. We flipped the white background for a black one. Amazon’s policy is to not automatically push revisions to customers unless they are judged to be very serious or significant, and new cover art doesn’t rate. So these covers will appear for new buyers only, sad to say. You can ask them specifically to push the new versions to you if you care about that sort of thing.
Here are a couple of the new ones: