George Clooney was surprised, back in January, to learn that “Grey’s Anatomy” was about to supplant “ER” as the longest-running medical drama in TV history.

“That’s got to stop!” he said with mock outrage. “We’ve got to go back and do some more.”

This came as he was surrounded by a group of reporters who were there to talk to him about his six-part adaptation of “Catch-22,” which starts streaming Friday on Hulu. A publicist kept telling us — at least a dozen times — that Clooney had to be elsewhere and we’d just asked our “last question,” but Clooney ignored her and just kept answering.

I’ve always loved Clooney. He’s always been open, funny, charming, unfailingly polite and astonishingly patient.

Sure, he wanted to promote “Catch-22” — he’s an executive producer, a director and he stars as Lieutenant, later General, Scheisskopf. And it’s a great miniseries that captures the hilarity and horror of Joseph Heller’s subversive 1961 novel about the insanity of World War II.

It centers on Capt. John Yossarian (Christopher Abbott), a B-25 bombardier who’s trying to remain sane as he tries to survive long enough to make it home.

It’s not just the enemy who could prevent that; it’s also officers like the parade-obsessed Scheisskopf and Col. Cathcart (Kyle Chandler), who keeps raising the number of missions that crews have to fly to be rotated back home.

And, by the way, Chandler is another of Hollywood’s amazingly good guys. Maybe less shy than he seemed in 1991, when he was a virtual unknown starring in “Homefront,” but he still has the same sort of ease, earnestness and humor. You almost believe him when he says he brought Clooney “coffee every morning” during production.

“Catch-22” is funny and dark simultaneously. The production values are amazing, and the performances and direction (Clooney, Grant Heslov and Ellen Kuras each helm two episodes) are great. It’s terrific television.

Clooney’s character is a pompous jackass; Clooney is anything but. Abbott joked that he went to IMDB.com to look him up and “It was, like, ‘Oh, you’ve done a lot.’ I didn’t know.” Clooney came back quickly:

“I’ve been working for a long time now. I’m very famous,” he said smoothly. “Big, big star. You just didn’t know that. You’re too young.”

Only Clooney — and maybe Tom Hanks — could say that without a hint of ego, just self-deprecating charm.

He seems like the same guy I remember chatting with one-on-one nearly 27 years ago, when he was starring in a short-lived police drama, “Bodies of Evidence.” At the time, George’s father, Nick Clooney, was anchoring the news at KSTU-Channel 13 in Salt Lake City, and I asked George if he wanted me to tell his dad anything when I got home.

“Tell him I was really drunk and there were women hanging all over me,” George said with a laugh.

Neither was true. This was pre-”ER,” and — though he had a long list of TV credits (including “Roseanne” and “Facts of Life”) — his career hadn’t taken off yet. That happened two years later with the debut of what is now the second-longest-running medical drama in TV history.

“‘ER’ was a nutty moment in my career, but also in the lives of a bunch of actors,” Clooney said. “There were six of us who suddenly were thrust into the stratosphere, and it was life-changing for all of us.”

Since then, he’s won a couple of Oscars (with four more nominations), starred in movies like “The Descendants,” “Syriana,” “Michael Clayton” and “Ocean’s Eleven,” “Twelve” and “Thirteen”; directed movies like “Good Night, and Good Luck” and “Monuments Men” — and, yes, become a “big, big star.”

But not too big to joke about himself, and about making some new episodes of “ER.”

“Don’t you think that’s a good idea? I’d play a patient now,” Clooney said.