cool surprise from amazon

I recently preordered the latest Harry Potter book from amazon.com as an early birthday present for my wife.  I paid $17.99 (40% off the cover price) + shipping for guaranteed delivery on the release date (or shipping would be refunded).  It arrived on time as expected, and my wife was very happy about it.  As an added bonus, I got this unexpected email from amazon!:

From: Amazon.com <order-update@amazon.com>
To: [REMOVED]
Date: 16 Jul 2005 22:31:58 -0700
Subject: Your Amazon.com Order for Harry Potter and the Half-Blood Prince (Book 6)
-------------------------------------

Hello from Amazon.com.

Good news!  We've just lowered the price of "Harry Potter and the
Half-Blood Prince" from $17.99 to $16.99.

You don't need to do anything to get the lower price--we are automatically
issuing you a $1.00 refund.  This refund should be processed in the next
few days and will appear as a credit on your next billing statement.  We'll
also send you a follow-up e-mail to confirm the refund once it has been
completed.

Thanks again for shopping at Amazon.com.  We hope you enjoy your book!