In 2013 at Nelson Mandela’s memorial service, Helle Thorning-Schmidt snapped a photo with U.S. President Barack Obama and U.K. Prime Minister David Cameron that—at the time—was heard round the world (or at least ricocheted quite frantically around the internet). The shot, which she describes as her first-ever selfie, prompted stories like “Barack Obama ‘selfie’: who is Helle Thorning-Schmidt?” to run online.

“When we came to the stage there was no seating,” she told Fortune‘s Most Powerful Women International Summit in London on Monday. So she sat down next to two empty chairs marked “reserved.” She thought that she’d simply scored a lucky seat, not knowing that Barack Obama and First Lady Michelle would soon take the vacant spots to her left.

As other attendees came to request photos—”With Barack,” Thorning-Schmidt said, “not with me.”—David Cameron sat down to her right, and she chatted with the Prime Minister casually.

She described the atmosphere as “jolly” and since her children had just taught her how to take a selfie, she took the opportunity as a chance to test out the technique.

“I said, ‘We’re going to have a selfie,’ and I took the selfie,” Thorning-Schmidt said. “The three of us had forgotten in the moment that it wouldn’t be our little selfie moment to the three of us.”

Indeed, the photo went viral—in part because Michelle Obama, sitting nearby, was left out.

Thorning-Schmidt, who was Denmark’s first female prime minister, saw the President a little while later. “He told me, ‘You got me into trouble,'” she said, “It wasn’t with Michelle,” she insisted.

She says she now gets photo requests all the time. The episode has turned her into what she called, “the selfie queen.”

Reflecting on the famous photo and the hubbub surrounding it, Thorning-Schmidt said Monday that it took her a while to determine what the whole incident meant. “Because it made me so famous,” she said, “I tend to think it was a good thing.”