If I remember, nobody authoritatively claimed that he took anything else physical but copied the secret data to the USB stick. If he had to use a stick then there were never notebooks with secret data that he could take.

Some article somewhere mentioned that he carries 4 notebooks, and then the press started fear mongering and compromiting him by insinuating that the notebooks are full of secrets and government property. Can anybody quote an official claim that the notebooks aren't his own?