 He notices as she pulls out of her purse there's a receipt from a hospital, and she imagines that maybe they've been dealing with a serious medical issue in the family. Maybe one of her parents is struggling with a serious medical issue, and that has her stressed. Anyway, he starts imagining the back story on everyone that's annoying him and making him mad at this grocery store, and he realizes that if he knew everyone's story, he couldn't hate him.