yeah that's strange that it happens right when the btc was peaking...
lets make some speculation:
Say you have some other wallets aside the cold one belonging to the customers and want to make some profit fast:
* announce that you have been stolen your cold wallet
* close the site
* dump the btc from the other account
* in the mean time because of the announcement, btc goes down
* rebuy all the btc you just dumped at lower value
* found (or not actually
![Grin](https://bitcointalk.org/Smileys/default/grin.gif)
) the lost btc
* reopen (or not) and enjoy the profit
definitely an inside job...