The chronology in this report from The Hill is kind of garbled, but it says both that
a) President Obama "was heard on an open mic telling an official at an event last year that it was Michelle Obama who 'scared' him into quitting smoking. A smiling Obama said at the time, 'I haven't had a cigarette in six years … that's because I'm scared of my wife.'"
b) Mr. Obama told Billy Joel when the singer visited the White House last year, "I'm going out on the North Portico to have a smoke. Do you want to come with me?"
I don't mind if Mr. Obama smokes, but it does seem a bit strange that he'd be trying to convey the public impression that he's more scared of his wife than he actually (apparently) is.