“Gossip Girl” star Leighton Meester and Adam Brody, the heartthrob of the defunct Fox show “The O.C.,” have been dating for several weeks, reports Us Weekly. The actors have been racking up frequent-flyer miles. In January, they were spotted at the Siam Kempinski Hotel in Bangkok. On Friday, Meester and Brody, who co-starred in the film “The Oranges,” were spotting perusing an exhibit at the Los Angeles County Museum of Art.