why does Sheila run out of the room with a little cry halfway through the first act ?

Eva worked at Milwards very happily until, after a couple of months, she was suddenly told that she had to go. There was nothing wrong with how she was doing her work, but, the Inspector adds, a customer had complained about her. The Inspector shows an agitated Sheila the photograph of the girl, and she runs out of the room, clearly having recognized the girl. Birling, angry with the Inspector’s behavior, follows after her.