D.C. Mayor Muriel Bowser (D), her chief of staff John Falcicchio and former mayor Adrian Fenty at a birthday happy hour for Falcicchio at 12 Stories in Washington on May 13. (Khalid Naji-Allah)

Hey isn’t that . . . D.C. Mayor Muriel Bowser throwing her longtime staffer a 40th birthday bash?

On Monday night, Bowser toasted her Day One chief of staff, John Falcicchio, at the trendy new 12 Stories bar on the Wharf. Former mayor Adrian Fenty was also on hand to celebrate Falcicchio, who’s worked with Fenty, the Democratic National Committee and former Sacramento mayor and NBA player Kevin Johnson.

The Washington VIP crew, which included Kastles owner Mark Ein and former D.C. police chief Cathy Lanier, knocked back Casamigos margaritas and burgers. Bowser, who planned the affair, invited her inner circle with a personal text that read, “Hail to the Chief.”

12 stories, which opened just this month, has already hosted a bevy of famous faces including Redskins player Vernon Davis and actors Tim Daly, Anthony Rapp and Dean Norris.