Amazon.com: "Promotion applied" discount? (NOT complaining)

Factual Questions
1

The last two times I ordered things from Amazon, I’ve gotten a substantial discount, but I can’t figure out why. One order was actually free after the “Promotion” that was applied, and the other order went from being a $30ish order to $7 and change. In both cases, the line item with the discount read “Promotion applied.”

Did I just randomly chance onto some promotions that Amazon was having? If so, how the heck do I figure out what’s on promotion, because those are awesome deals! Did I have some credit on my account that I didn’t know about?

I hesitate to ask Amazon because, well, they might take it away.

2

Did you recently apply for an Amazon Visa card? I believe that the $30 credit is applied to your order(s) on the “Promotion applied” line.

3

No… but now I’m wondering if someone else has, in my name.

4

Mystery solved!

6+ months ago, I complained about the delivery time of something I ordered at Amazon. I just remembered that they gave me a credit “for my trouble”. I guess I hadn’t ordered anything else from them since then; I had totally forgotten about it.