Last night, only hours after the Federal Reserve made its first big interest-rate cut in four years in an attempt to stanch the leaking housing and credit bubble, iconic former Fed chief Alan Greenspan had something to say. On the occasion of his new memoir topping the best-seller list, the finance gnome was grilled at the 92nd Street Y before a packed house — by none other than his wife, veteran NBC correspondent Andrea Mitchell. "I'm torn between proving my objective journalistic values and wanting to save my marriage," Mitchell confessed early on. She seemed to favor the former impulse by dogging 81-year-old Greenspan, twenty years her senior, on whether he helped set up the current bust by repeatedly lowering interest rates post-9/11. "Guilty or not guilty?" she asked him. When Greenspan pleaded the latter, she reminded him that other experts had warned that super-low rates might fuel a backfire. "If you had some inkling, why were you so bullish about adjustable-rate mortgages?" she persisted. (Greenspan said that he'd only promoted ARMs on prime mortgages, not forseeing the subprime implosion that's driven the current chill.) Mitchell concluded by asking her owlishly visaged old hub a question submitted from the audience: How do you deal with stress? "Have your wife talk to you nicely and pleasantly," the Oracular One grumbled.