What does Freddie do to rouse Mavis' jealousy in The Most of P.G. Wodehouse?

In "Fate," Freddie does a good deed by helping a woman with her luggage. Freddie thinks that because the woman is not attractive there could be no misunderstanding of his intentions by helping her. However, Mavis does not trust Freddie's motives, and Freddie must try to reassure her.