What does Mrs. Dalton say to Peggy that begins to threaten Bigger's story?

During their conversation, Peggy and Mrs. Dalton become alarmed when they realize that Mary didn't pack all of her things in the trunk Bigger took to the station. Mrs. Dalton questions Bigger once more about Mary's actions, but doesn't take the matter any further. In fact, she gives him the rest of the day off. Regardless, the incident worried Bigger because he hadn't thought that far ahead.