I would bet that it was found by the crew that cleans the plane. And rather than actually turn it in to lost and found like an ethical person, they took it home. I haven't lost many things over the years on a plane, but whenever I have, I've NEVER EVER gotten it back despite phone calls to the airline very soon after the loss. The airlines don't give a fig. I would write a letter of complaint to the airline on the lack of either ethics or thoroughness. They either stole it or they didn't find it when they cleaned and another passenger on a later flight took it.