What significance does Mama's memory of having been hooked in the side while milking a cow coincide with the climactic moment of the story?

From the beginning of the story, it is clear that mama is an exceptionally strong women (physically and mentally).  Being hooked by a cow emphasizes her strength; despite her injury, she did not become weak.  In addition, the mama states (as narrator) that she loved to milk until the cow hooked, or hurt, her.  At the climax of the story, when Wangero/Dee tries to take Maggie's quilts, not only does mama stand strong, her feelings for Wangero/Dee also change.  She no longer accepts Dee's behavior without asking questions or resisting.