Ever since I got my K1 almost two years ago now, I keep reading these sorts of posts. Almost everybody has had outstanding service from Amazon, and many people who got defective ones had the same great experience that you did.
I must admit that a two-piece button is a new one though.
I only have called CS a few times, and always got a quick answer or solution. The first cover I got did not fold back properly. I called them and they rushed me a replacement and did not even want to original cover back.
Ah, if only every other business has such wonderful service as Amazon! They are equally good at handling non-Kindle problems too.