I agree it does sound like the scam described on here, but there's another possibility I've thought of:
Amazon saves all the previous gift addresses I've used as do other companies, and if the last purchase I made was a gift, when I order next time I have to be concentrating and change my address back to mine IYKWIM. I often don't get any invoices at all in amazon buys if it's not from amazon themselves.
Another Tired Kicking For The Sick And Disabled By Rishi
Do you still have all your own teeth?