In a way it was like dragging information out of Peter, although with some obvious differences. For starters, Gamora knows that they are strangers, and she in turn would exactly go spilling everything either. Even with the Guardians, there are some things that Gamora hasn't shared...

"And that would be?" There is a brief moment where she wonders after Thanos, but she has made certain not to pass knowledge on to him when she had been there. Without it, it would greatly hinder his search. "But you do now, believe them?"