Sure, but it's in the same category as the owner putting up a sign by mistake, or omitting to update a sign by mistake. Or more realistically, an employee of the owner putting up a sign even though the owner had instructed him to put up a different sign.
No, in this case the shop is legitimately offering an item for sale, and then forgetting to change the price they are offering it at. It's quite disingenuous for a shop to put up signs, and then act like those numbers aren't legally binding, while the real prices are hidden away in a database somewhere. If they want to have their database be the authoritative copy pricing information, then they can just not put up price signs to begin with.
