Washingtonian owner Phil Merrill showed up at his magazine's offices a week ago, surprising Editor Jack Limpert and the staff. Merrill, who is assistant secretary general of NATO and lives in Brussels, doesn't come to town very often. He confided to Limpert that he was suffering from gallstones and was scheduling an operation for a hospital near his home in Annapolis. Limpert gathered up some color photographs from an article scheduled for the March issue of Washingtonian on a laser gallbladder operation.

Merrill called the author of the article, Neil Ravin, who put him in contact with physician Richard DeRosa, who is featured in the article. DeRosa operated on Merrill Friday at Sibley Hospital, and the NATO official went home yesterday for a brief period of recovery before returning to Brussels. Feeling a bit superstitious about the timing of the magazine article and his gallstones, Merrill advised Limpert, "Don't do any stories on open-heart surgery." Out and About

Sen. Patrick Leahy's son, who is in the Marine Reserve, is expected to be stationed in the Persian Gulf soon. According to the Congressional Quarterly's Insight Newsletter, Mark Leahy, 20, has taken a leave of absence from the University of Vermont to report to Camp Pendleton, Calif., for training, after which he is expected to report to Operation Desert Storm. The Vermont Democrat said he would not comment on his son's deployment because he considers it a personal matter ...

With this year's Miss USA pageant only a couple of weeks away, Ziba Ayeen, Miss Nebraska, has some concerns: She may be called to active duty in the Persian Gulf. The 26-year-old native of Afghanistan, who moved to the United States in 1980, is an Army National Guard medic. "All that we have been told is there is a good chance it could happen," she said, referring to the possibility that her unit would be called to active duty. "I'm willing to go with my unit if it is activated," she said. "I just hope it wouldn't be in the next two weeks" ...

Former Reagan speech writer Peggy Noonan, who had a best-selling book about her eventful, influential years at the White House, has decided to give up her column in Mirabella magazine. According to columnist Liz Smith, Noonan is going to devote all of her creative energies to her first novel ...

Actor Paul Newman, known for his donations to a variety of charities, has again made a donation to the Missionary Vehicle Association, a Washington-based organization that provides forms of transportation -- including jeeps, boats, trucks and motorcycles -- for American missionaries working in developing countries. Newman's $28,000 gift from the profits of his spaghetti sauce, popcorn and salad dressing is the fifth he has made to the association, for a total of $171,000. Newman became involved with the organization through a friend, champion race car driver Mario Andretti, who is also a friend of the Rev. Phillip De Rea, the association's director and chaplain of Champion Auto Race Teams. Andretti also serves on the group's board ...