What did cassie do that Mr Simmons said she had to apologize for?

Cassie bumps into Lillian Jean Simms, who is with Jeremy and their two younger brothers. Lillian Jean demands an apology, which Cassie reluctantly gives, and then tells her that she should walk in the street. Cassie is trying to keep from being pushed off the sidewalk by Lillian Jean when Mr. Simmons appears and twists Cassie's arm behind her back. He demands that Cassie apologize to his daughter, although Jeremy insists she already did.