I've had postal workers take money out of envelopes or even CDs out of jewel cases, so I know that kind of thing happens.
However so far as I can tell, everything was factory sealed and the mailer wasn't tampered with in any way. These were sent to me straight from JH via Moon Audio.
If I had to guess, I'd say they were just really swamped with trying to get orders sent out, and in the fray somewhere along the lines someone forgot to put the earphones inside the metal jar when packing everything. Unfortunately there are no serial numbers listed on the box or any materials inside the box (which is pretty spare aside from accessories), so I have nothing to relay to anyone, who in turn have no real way of looking for any missing earphones.
Anyway, we contacted Drew who quickly got ahold of JH. They were apologetic and said they were sending a replacement via overnight delivery. Case closed, hopefully!