Hannah asking who's there rather than opening the door? Something must really be wrong! But where Justin would normally put on a laughing smile and stroll into the flat, intent on grabbing her into a bear hug to take away whatever was bothering her, he now simply leaned against the door jamb.
"It's Justin," he said, his natural ebullience absent from his voice. "I was, um, waiting for you downstairs. You didn't see me when you got in."