The silence after someone says 'I'm fine'

It’s not the lie that bothers me—it’s the way the air changes. Like a door clicks shut, but no one’s left the room. I’ve heard it in the library, in the checkout line, even on the phone with my sister. That particular kind of quiet where the words are done, but the weight isn’t. I wonder if anyone else notices how long it takes to start breathing again after that.