S delivers goods to B pursuant to a contract for sale. B pays for the goods when they arrive and then inspects them, at which time she discovers that they do not conform to an express warranty made by S. The nonconformity is not material but B in good faith does not want the goods. She writes a letter to S indicating that she will not keep the goods, stating the nature of the nonconformity, and demanding a refund of the price she paid. Which of the following statements is correct?