“NCIS” actor Mark Harmon was spotted outside the White House. (Cliff Lipson/CBS)

Hey, isn’t that … actor Mark Harmon, a.k.a. Special Agent Gibbs of the hit show “NCIS,” poking around the White House’s northwest gate on Sunday?

Unlike the oblivious tourists and protesters, our tipster, photojournalist Greg Mathieson, recognized the 64-year-old actor — black jacket, and a scarf to match his silvery hair — and stopped for a picture and a chat as he was leaving the White House. Harmon told Mathieson that “NCIS” would be filming Monday outside the White House and later inside the building.

The biggest news Harmon broke? First lady Michelle Obama will be part of a scene.