While President Trump made his first post-election remarks to discuss the Pfizer COVID-19 vaccine, his silver-toned hair, a variation on his trademark blond locks, caused a stir.

During the live press conference Friday, the president elaborated on Operation Warp Speed, an effort to deliver a free COVID-19 vaccine to the public and his commitment to preventing another nationwide lockdown.

However, his hair appeared to be a different shade, noticeably grayer and less blond than usual, and Twitter took notice.

Trump’s hair has offered intrigue for its distinct comb-over style and yellow-blond hue. In the 2018 book Fire and Fury: Inside the Trump White House, writer Michael Wolff claims the president’s daughter Ivanka describes his coif as “an absolutely clean pate — a contained island after scalp-reduction ­surgery — surrounded by a furry circle of hair around the sides and front, from which all ends are drawn up to meet in the center and then swept back and secured by a stiffening spray.” The color, wrote Wolff, is achieved with the drugstore brand Just for Men.

Could Trump be in on the joke? In March, he delivered remarks on the growing coronavirus pandemic, revealing a lighter set of locks. “And my hair is blowing around, and it’s mine,” he said. At the time, historian Alexis Coe told Vogue of his look, “It’s about optics — Trump is trying to distract from his late, dangerous, and sometimes fatal messaging around coronavirus.”

Perhaps the president’s most recent gray look was a consequence of lighting, dark stage makeup, an ashier dye or age (when he was elected in 2016, President Trump, then-70, was the oldest president to take office). Stress could also cause hair to turn gray, as Harvard University researchers discovered in a January study conducted on mice, due to hair follicle damage caused by the physiological “flight-or-flight” response.

Trump shares a commonality with past presidents who underwent hair transformations. President Barack Obama, who held office from 2008 to 2016, grew grayer during his two-term presidency, however he denies that his high-stress job was a factor. “My grandfather was gray by the time he was 29. ... So I figured it was going to come. It just happened to coincide with the presidency,” he said during a 2011 interview with ABC News.

But wife Michelle Obama refused to call him a “silver fox,” his nickname on social media. “He regrets that he hadn’t dyed his hair before,” she said in 2018. “It’s like, ladies, hair dye and diet and exercise! If it weren’t for his gray hair, he’d look good too!”

While President Bill Clinton, who served from 1993 to 2001, went gray even before taking office, according to Jim Miles, his former hairdresser in Little Rock, Ark. “He’s always been too busy to worry about it,” the salon owner told the Los Angeles Times in 1993.