Act 3 scene 2

She does not really clue into the fact that Claudius is disturbed by the play because of he murdered his brother. This tells us that Gertrude knew nothing of how her first husband was killed. More importantly, she is uncomfortable with the narrative of the play. She feels self-conscious about the Player Queen's protestations of love to her husband, Player King. Gertrude thinks the Player Queen is over dramatizing things,

The lady doth protest too much, methinks...