Twenty years ago, they would have been throwing china at each other. But once-warring Madonna and ex-husband Sean Penn were spotted “laughing and chatting” over dinner at Alain Ducasse‘s Adour at the St. Regis Thursday night. The couple, who divorced in 1989 after a four-year marriage so fiery they were dubbed the “Poison Penns,” shared a long meal. A spy told Page Six, “They seemed to be getting on so well, we had to look twice to make sure it really was Sean Penn she was with.” A rep for Madonna told us, “Penn stopped by the table to say hi.” But our spies insisted it was just the two of them with their security for hours. No word on what was making Madge laugh, but at last year’s Oscars, Penn famously gestured at her 23-year-old boy toy, Jesus Luz, and cracked, “Another kid already?”