Grading a note with a minor bend in the corner
I sold the note shown below as crisp uncirculated (no number, no choice/gem-type modifier). The note definitely looks uncirculated to me, but the buyer sent it back as damaged/incorrectly described/not uncirculated because of a crease in the upper left corner. On second view, there is a minor bend, and the corner doesn't lie fully flat, but my definition of a crease is a much sharper crease than what's here. You can see the "crease" if you look at the photo carefully.
For my own understanding of grading and for how to deal with this return, did I describe the note incorrectly? Reading PCGS and PMG grading standards, they mention folds, but again, I'm not sure what exactly qualifies as a fold.
Any help you can provide would be greatly appreciated.