Culd it have slipped between pillows in couch or chair? (I guess after a month that it would have been discovered if that was the case, but I'm grasping at straws here!)
My guess: You had it in your hand when you went to do something totally unrelated, and then just put it down in a really really odd place (for a reader at least). Have done that with different things, and they are darn near impossible to find if you can't backtrack wheat you were doing when it disappeared.
So sorry to hear of your (apparent) loss! Hope you find it and when you do, please let us know where on earth you put it!