SR4A page 329, page 25 of Unwired. More is in the SR4A master index.
I've browsed those again, still no clue. There is no obvious, active RFID. Had there been any I'd have told you already.
The test is to either find hidden node of active rfid, that is not broadcasting on any radio frequency (like in the case of RFID programmed to go-live once every hour for example on microsecond long burst.) and for fiding rfid physically if it is glued somewhere within the stick. (which is the size of the pendrive). The difficulty is in opening it, so it can be put back together and finding little bugger.
Of course until you are sure there is something within, you cannot remove it. RFID eraser will cleare it for sure, but there is a chance for credstic clearance as well (it's usign magnetic field, to disrupt tags operation).
As of now you haven't found it - there is no visible or active rfid tag attached.