gesture quite interesting too.

]I wonder at Darcy's involuntary drawing up of the chair closer to Lizzy? JA never seems to put in details for no reason.

Their conversation was on the distance a woman could be from her family. He probably felt that Lizzy, being different from any of the other women in that neighbourhood, had spent more time away from from Longbourn. She had a better-informed mind, was intelligent, etc., etc.. He might feel it absurd that she should be talking with such a strong local attachment, and seems to have lost control for just a minute there.