One, the 29th century Drone, accidentally reactivated his Beacon which Seven and the Doctor had turned off.
Seven uploaded the complete repository of her experiences on Voyager back into the Collective during Dark Frontier, and so did Tuvok.
You would think that because of the wireless interfacing, that Just waking in proximity of another drone or a Cube would cause an electronic handshake where seven dumps everything she has, while receiving a number of updates and patches from the collective.
Seven of Nine would have to have unexpected firewalls and enhanced encryption to keep the Borg out of her thoughts who would surely be confused as to why she is not an open book?
I still laugh about how easily Ransom (and even Starling or Dr Giggles.)reprogrammed the Doctor because the Doctor had NO encryption or even passwords protecting his software.