"He was right there. Why not? It's Mr. Buffett," said Powell, explaining why he asked for the autograph. "He's wonderful."
Powell said he'll probably frame the coat and display it at work when he returns to California.
Dozens of Utah coal miners picketed outside the doors of the annual meeting in downtown Omaha.
The protesters are members of United Mine Workers of America who work at Deer Creek mine near Huntington, Utah. The mine is run by a subsidiary of Berkshire's MidAmerican Energy Holdings Co.
The union's contract expired in January. The company and union are negotiating, but disagree on health care coverage and safety checks. The protesters hope to influence Buffett.
Bernie Morris of Price, Utah, stood in the rain with others Saturday to hand out flyers. The 67-year-old Morris said he's worked for the coal mine for 28 years. He feared that he and his wife won't be able to afford the monthly health insurance premium the company wants to charge miners and retirees.
Berkshire shareholders should expect decent returns on the newspapers the company has bought in recent years, Buffett said. But he doesn't expect the papers to generate enough profits to make much difference to Berkshire.
Berkshire has paid cheap enough prices for the newspapers that Buffett expects them to deliver 10 percent returns every year, but he also expects their earnings will keep declining.
Berkshire has acquired 28 daily newspapers over the past two years.
Berkshire Vice Chairman Charlie Munger pointed out that Buffett made an exception to his usual investing habits for newspapers because he likes them.
'GANGNAM STYLE' WARREN:
Buffett again poked fun at himself in the humorous movie that begins the Berkshire Hathaway annual meeting.
A cartoon version of Dancing With the Stars opened the hour-long movie.
Buffett and Munger served as judges on the dance show as representatives of different Berkshire companies competed.
In the end, Buffett and Munger won the competition themselves with their version of "Gangnam Style" dancing.
In a live-action video later, Buffett tried to pull strings to win a part in Arnold Schwarzenegger's new Terminator movie.
But Schwarzenegger, who once relied on Buffett's financial advice as California's governor, decided that Munger would make a much scarier villain.