Getting back to the original question, I think the patron had a wild hair about something else, and was taking it out that way.
We don't go out all that often, and when we do it's to fine-dining places. Thus, I'm not interested in the price of the special. I expect it to be higher, and just don't care. And, in fact, I think it beyond tacky for the server to mention it.
In Joey's case, we're talking about a regular practice of not mentioning the price, a special that isn't particularly out of line with menu pricing, and a regular customer. There's no justification for her complaining. Indeed, just the opposite. Knowing how things are done in that restaurant, if price was an issue for her, it's her obligation to ask.
I'm not saying this is the normal practice. Most people do want to know the price up front. It's incredible, in fact, how many people read a menu from the right hand side first. So, yes, in general the prices should be given. But this isn't a general case. It's a very specific instance, and all factors should be taken into consideration. When that's done, I believe, the customer's complaint was off the wall at best.