I was looking through my bubble mailers, which are mostly reused from books that I requested, and I came across one where I couldn't remember offhand what book I got from it (yeah, it's a weird thing to suddenly wonder about, but bear with me ^_^). It still had all the labels and stickers, so I decided to look it up in my transaction archive, and...there is no transaction I can find that corresponds to the postmark date, tracking number, or sender's name or location. This mailer seemingly came out of nowhere. Is there any circumstance that would prevent a transaction from showing up in my archive? The only other thing I have is the Request ID, but I don't know how/if I can look up details using that.

Arrrrrgh, like a total dolt, I spent over an hour fretting about this, and as soon as I stopped thinking about it, the answer came to me. It was from my one and only transaction on SwapaDVD, which is mostly out of sight, out of mind to me. Sorry everyone, please carry on! *super embarrassed*

Don't be embarrassed. Asking questions is how we learn.