NEW YORK Something rare and wonderful happened at the opening night of the Encores! concert production of “Gentlemen Prefer Blondes” at City Center this month. At the end of the show, when the performers took their bows, the audience remained seated.

Let me add there was no doubt this audience had enjoyed mightily what it had just seen, a succession of showstoppers that climaxed with a knockout rendition of “Diamonds Are a Girl’s Best Friend,” that immortal anthem to nonliquid assets.

The number was sung by Megan Hilty, who gave the gold-digging Lorelei Lee character an original comic audacity that erased memories of Hilty’s most famous predecessors in that role, Carol Channing and Marilyn Monroe. It felt like one of those golden nights, so cherished by theatergoers, that thrust its leading lady into the firmament of musical stardom.

And at the final curtain, we stayed in our seats. We whooped, we roared, we beat our hands raw with clapping. But no one, as far as I could see, was standing up. “Gentlemen Prefer Blondes” had been accorded the five-star tribute of a sitting ovation.

I would like to make the case, officially and urgently, for the return of the sitting ovation.

Because we really have reached the point at which a standing ovation doesn’t mean a thing.

Pretty much every show you attend on Broadway these days ends with people jumping to their feet and beating their flippers together like captive sea lions when the zookeeper arrives with a bucket of fish. This is true even for doomed stinkers.

The SO (if I may so refer to a phenomenon that no longer warrants the respect of its full name) has become a reflexive social gesture, like shaking hands.

The reasons for the SO’s ubiquity have been pondered by cultural pundits. One theory has it that it’s because habitual theatergoers have become a rarity. Many who attend Broadway shows are tourists whose itinerary includes, along with visits to the Statue of Liberty and the Hard Rock Cafe, a performance of “Wicked” or “Jersey Boys.”

For such audience members, standing to applaud at the end of a show has become part of the Official Broadway Experience. And if you’ve spent several hundred dollars for that pair of orchestra seats, an SO seems to help confirm the money wasn’t wasted.

I also have a suspicion that for some people, standing immediately at the end of the show is simply a physical relief after an hour or more of immobility. Besides, the sooner you’re on your feet, the greater your odds are for beating the crowd to the exits. Let’s not discount the domino effect: Once the person in front of you is standing, you too must stand if you want to see what’s on stage.

I’m not asking for the wholesale abolition of the SO. That would be a sadly quixotic demand. I’m just asking you, my comrades in urban theatergoing, to think before you stand, if you must stand at all. And to remember, in an age in which the SO is as common in a Broadway theater as an endless line for the ladies’ room at intermission, that staying seated has become the exceptional tribute.