Remember the Jared Paul Stern gossip-ethics kerfuffle? The FBI does. Stern, a longtime freelance contributor to the Post’s “Page Six,” was accused by billionaire Ron Burkle of trying to extort $200,000 from him in exchange for keeping negative stories about him out of the paper. Now the “Page Six” editor, Richard Johnson, has been contacted for questioning by a group that includes prosecutors from the Southern District and federal agents. Asked about a looming interview with the G-men, Johnson referred calls to a publicist. One of Johnson’s lawyers, Ed Hayes, says he is aware the Feds requested a routine sit-down with Johnson but believes it is unnecessary as Stern has not been charged with a crime. Because Hayes once represented Stern, he says another lawyer, Murray Richman, is representing Johnson in relation to the federal probe (Richman calls Johnson a “friend” but says he’s not involved; his daughter, Stacey Richman, is repping Johnson on a recent DUI charge).