Vogue creative director Grace Coddington says she’s still working on her memoir, but it’s stalled because her co-writer, Jay Felden, is settling into his new job as editor of Town & Country. “It’s slow going,” she told us during a screening of the Vidal Sassoon documentary at MoMA. Flame-haired Coddington, who stole the show in the Vogue documentary “The September Issue,” appears in the Sassoon movie because she used to model for the iconic hairdresser. Sassoon attended the screening with his wife, Ronnie, and guests Frederic Fekkai, Kelly Rutherford and Phillip Bloch.