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That does NOT look like metal fatigue. Prior repaired damage is more likely. Just because 'carfax' never recorded an accident doesn't mean someone didn't repair it themselves without reporting an accident. Clean carfax's doesn't mean 'perfectly fine'. Make sure you protect yourself by having an independent mechanic go over the vehicle carefully for signs like mismatched body parts or repairs. It WILL/DOES cost $ to have an independent inspection before purchase that might find instances of prior damage (there are pretty crafty resellers out there). In this case, the car is already yours so just find a part to replace it or have that part fixed/welded, and painted. Good luck!
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