If it matters for anyone about when the gash occured, I don't believe it occured randomly during transport back to the seller. The seller contacted me by PM over a month ago, saying that he'd read on another thread that I was an attorney and wanted legal advice. He said in that PM that the buyer mentioned a half inch gash on one of the shoes. I have no idea what this means, other than the seller was aware of the slashed shoes over one month ago and before they were shipped back to him.
OK. But the shoes had clearly been worn repeatedly, to judge by the condition of the soles . . . oh, never mind. I'm done.