This first happened to me about six months ago.  Everything I sell is "one-of-a-kind" and when I was unable to find an item that had sold I panicked.  It was some hours before I realized that the item had been bought a few weeks earlier by the very same US buyer.   I called eBay, and after a long time on the phone and being passed from one person to another, I was patched through to ebay.com as well.  The verdict: it was a very unusual glitch.  The next time it happened I was prepared.  Strangely, that was also to a US buyer.  Now I check every item against listings as a precaution.  This is possible as I'm just a small seller.