Yes, no doubt they're including a bit extra for the error. It's actions like that that keep me coming back to a firm. In fact, I'd rather pay more for something when I know the people behind it ARE behind it. My earlier-in-life notion of cheaper is better was very wrong.
Another thing I like about Williams is their willingness to ship out catalogs gratis. It's a rare instance where you'll find a merchant willing to bear the expense of producing then mailing a catalog without something in return first. Excellent place. IMHO.