In our home the incident would have a quite simple explanation. Since there are few horizontal surfaces that aren't "holding things," she quite probably laid the case down right where you found it, but in our place somewone inevitably would have laid something else on top of it.

Unless the search included the "dig and stir" method we use, the case would be unlikely to be found. All our piles look much the same, so it's not likely anyone could tell which one had been changed.

Someone later picked up the "thing on top" without seeing that the case was the next thing in the pile, and it was "miraculoursly" visible to the next person who recognized the "lost item."

YMMV. We do it a lot.

John