That is the point I was going to make. Often the seal has no factory defect in quality or workmanship, instead it got some weeds or twine or something wrapped up at some point that damaged the seal. A damaged seal is not covered by warranty, it needs to be defective to be covered. A defective seal does not take a couple of years to start leaking. That being said, I'd still advocate to cover this to keep a customer happy, but I really doubt it is a legit warranty issue. Keep in mind the customer won't usually know he wrapped something up in the seal, as far as he knows it just started leaking, so it's an honest request that he feels it has failed.