Jhustis was already awesome and got me the sigil I lost due to this bug back, but I figured it could hurt to post about it too in the very rare event someone else tries to use one of these on flying carpets, too.
When the carpet turns from a boring old rug to a flying thing of awesome, it ends up forgetting it's bonded. The bond 100% breaks and you get the messaging about how you don't know what happened, but the bond you had with the item was severed forever.
Hopefully it's an easy enough thing to resolve, since I don't want to end up losing my carpet because I misplaced it.
"You always have to be a know-it-all. And you don't. Know. It. All." - GERSTEINJ2