Given that weight is such an important design element of an aircraft, ideally you would want the wing to fail at 150.00001 % of its design load. If it fails at 160%, you are probably carrying excess weight. I wouldn't be surprised if Airbus was purposely cutting their margins very fine in order to save weight. If the wing failed within a few percent of the target and if the results did indeed validate their finite element computer model then I would think that while structural modifications would definitely be required, a retest would not.