Amazon sent me an Amazon.com Gift Card worth $100?

[love blu or go home!]

Amazon sent me an Amazon.com Gift Card worth $100? Did anyone else get this? In the email it doesn't say I won anything or why the gave it to me.
Here is what the email said,
Redeeming your Amazon.com gift card is easy:

1. Visit our Web site at www.amazon.com
2. Select the items you want and add them to your Shopping Cart.
3. When you have found the items you want, click the Proceed to Checkout button.

You can claim your gift card by entering its claim code number right on the order form.

Not ready to use it yet?

Just add the gift card funds to your account so they'll be there when you're ready!

1. Go to Your Account.
2. Click "Apply a gift card to your account" under "Payment Settings".
3. Sign in with your e-mail address and password.
4. Enter your claim code and click "Redeem now". Your funds will automatically be applied to your next order.

For more information on using your gift card, visit www.amazon.com/help/gc

So I added the gift card funds to my account and sure enough now I have $100 bucks sitting in there. Just wondering why they gave it to me. I'm not going to call amazon and ask just wondering if any of you guys got it.