For the reader it is evident that O’Brien has tossed ‘bait’ . He had no proof of any kind that Winston was disloyal, and attempted a minor encounter.
Seeing Winston in the corridor of their workplace, O’Brien mentioned a particular book containing the most up to date version of Newspeak and offering to loan it to Winston.
The average sheep of 1984 would have responded with something like;
“I’ll wait until the Party distributes the Book,”
accepting their place in society, not willing to break, bend, or even step outside a boundary.
This would have been expected, but Winston was avid to go to see O’Brien.
The meeting could have been without the slightest question, if Winston arrived alone, and simply focused on borrowing the book. But this did not happen.
Winston’s avidness made it clear he believed there was some conspiracy in which O’Brien was involved that he wanted to join.
This was serving himself for lunch.
What makes it even more tragic is that instead of going alone, of being cautious, he takes Julia, exposing her, and then, rabidly agreeing to do whatever is asked of him.