Honestly, at $1,800 a pair and with a reputation to maintain, St. Crispin's should offer to remake your shoes. They have made more than enough pairs to know that this type of thing can happen, and should have warned you that this pair could have these types of stretch marks. You aren't some litigious asshole and you know what nice stuff is. It would not be rude or gauche to ask them to correct this problem. $1,800 for a pair of shoes is probably be equivalent to driving a Porsche 911 Turbo S in the car world. Imagine if the headlights started fogging up. You'd definitely bring it in to be corrected and Porsche would do so free of charge. It would be a disgrace, however, to treat $1,800 shoes like beaters.