Anytime
This bag is stitched together inside out, then turned back, so the stitches around the corners get stretched. And since the Vuitton sewing machines are monsters, they tend to make enormous holes and in some cases they show. In most cases they won't tear more. I wouldn't be surprised if that was there from day 1. But I totally understand that it doesn't look nice. I'm afraid they won't consider this a defect though.
Here is a press photo of an Empreinte Multi Pochette, the stitching holes on the side are like little tears:
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And this other pic of the underside of the Alma BB handle shows how ruthless those machines are, very pronounced holes:
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