The silence after someone says 'I'm fine'

I was shelving returns when a kid came in, late book in hand, and said, 'I'm fine,' with that flat, practiced tone. I nodded and took the book. The silence that followed—just the hum of the AC and the rustle of pages—felt heavier than any confession. It’s not that I believe they’re lying. It’s that I know how much weight a single word can carry when it’s not meant to be heard.