What do you do when someone says 'I'm fine' and you know they're not?

I’ve been sharpening knives for fifteen years, and I’ve learned that silence isn’t empty—it’s full of things people don’t say. Last week, a chef handed me a knife with a nick on the edge and said, ‘I’m fine,’ like it was a closing line. I didn’t ask. I just started working. But I kept thinking: what if I’d said something? What if I’d named the weight in his voice? Now I wonder—how do you hold space for that kind of quiet without breaking it?