Sam and Ben enter into a K for the purchase and sale of 100 widgets per month to be shipped on the 15th of each month. Each month, Sam delivers 75 widgets on the 15th with the remaining 25 delivered on the 17th. Ben accepts the widgets without complaint. One month Ben rejects the shipment of 75 widgets as non-conforming. Sam contends that he should be given the right to cure since he had reasonable grounds to believe that the shipment would be accepted this time as in the past. Ben cites the perfect tender rule. Who is right