Brad, what someone steps up to do after the sale is done speaks volumes of the seller...but it's fair that the buyer be prepared for the worst since it's up to the sellers discretion what else they'll offer up post sale.
(Brad made my first PTW purchase a success...well not stress free, but it worked in the end!...like a PTW broken record...he built it, tested it, shipped it, I received it, shot it and it died by the third day

. He took a 2 hr phone call from me to try and figure out what was wrong, then split the $500 cost of a VUK with me to fix it and turn it around by the end of the week. It's worked like a freaking dream ever since. Stand up guy...aces. I didn't expect that...but I was forever grateful)
I've done the same....fixed or refunded stuff that had a 100% statisfied completed sale. I once refunded a pistol that that I shot, the guy shot and we were all smiles before he bought it. Then the next day it quit on him. I tried to fix it and couldn't. I insisted that he take his money back (he didn't ask and nearly refused)...but you know, he was a good guy and I didn't want him to be stuck with something and I felt good with that.
I'd hope that everyone would stand up like that...but I wouldn't count on it.