> So maybe I'm ignorant here, but did they do the transfer over the Internet, or was it a thumb drive taken out of "cold storage" and handed off to someone else.

Every bitcoin is controlled by a private key. The private key can be put in 'cold storage', but if I hand you the USB key with a private key stored in a text file on it, you have no way of being sure that I didn't keep a copy elsewhere and in a few minutes will make a transaction sending it to some other private key (which you don't have). So unless you trusted me an extraordinary amount, you would immediately want to make a transaction transferring from the private key on the USB to a new private key you generated just that moment.