The actor Bryan Batt’s best stories are about his mother. No wonder: “She Ain’t Heavy, She’s My Mother” is a title to be reckoned with, and so is Gayle Batt, the steel magnolia whose son plays Sal Romano on “Mad Men.” Mr. Batt — “Pumpkin,” to Gayle — engagingly tells his family’s story through good times and hard ones. His acting career has had its ups and downs too. (He was a cat in “Cats.”) The pièce de résistance: his mother arrived to watch the shooting of the “Mad Men” Season 3 premiere, in which Sal figures prominently. Mrs. Batt had to be warned by her son that she’d be watching a scene in which Sal is explicitly groped by a bellhop. “Pumpkin,” she answered, “I can’t wait.”