If second-term presidents feel liberated by reelection to pursue bolder agendas, first ladies often become more comfortable to be their own person.

Witness Laura Bush, who in her husband’s second term discovered that she, too, had a voice and a bully pulpit. Seemingly overnight, she transformed herself from librarian to liberator, becoming a voice for oppressed women — from advocating for Burma’s Aung San Suu Kyi, the democratic leader then under house arrest, to spearheading a women’s health movement across the Middle East.

Likewise, it appears that Michelle Obama has begun to break out. Though she long ago established herself as a health-and-fitness mom in chief, she had until recently been careful to stay well within the lines of traditional first lady. Obviously accomplished in her own right, she spent the past four years fashioning an image of good wife and mother to counter early impressions of her as politically ambitious and, to certain of her critics, angry.

Whatever she was then, she is something else now. In her second term, Michelle Obama has come out with, well, a bang! She isn’t just breaking the mold; she’s shattering the good china. The Madonna of first ladies, she is emerging as an iconoclastic, self-reinventing woman who clearly doesn’t mind shaking the firmament. It seems clear that no one, including the president, tells the first lady what to do.

“She always looks good” was Barack Obama’s wise response when asked how he liked his wife’s new bangs. Studies have confirmed what all successfully married men know: The correct answer to any question is “Yes, dear.”

The bangs were a clue that Michelle was evacuating the cocoon. Analyzing her bangs may seem a silly pastime — but only if you know nothing about women. When a woman changes her hair — especially as dramatically as the first lady did — something is up.

Those aren’t bangs covering Michelle Obama’s eyebrows. Those are butterfly wings.

Observe. The first lady completely changed her appearance on the eve of her husband’s second inauguration. Now why would she do that? She jokingly has said that her bangs were her midlife crisis. Cute answer, but it’s clearly more than that. Hair is the frame we choose for the portrait we project to the world. Hair conveys messages we don’t even consciously recognize.

Who knew that Michelle Obama harbored an inner Gidget? Cute, fun-loving, perky were not adjectives that sprang to mind when Michelle became a household word four years ago. That was then. Michelle Obama obviously has decided to have some fun.

Thus, recently, she joined Jimmy Fallon in a viral pas de deux titled, “The Evolution of Mom Dancing.” Sunday night she crashed the biggest party on television — the Academy Awards — to announce the best picture winner. Appearing remotely on a gargantuan screen like a holographic Princess Leia, she was a glimmering, spaghetti-strapped goddess beaming in to bestow the grand prize — Herself — on the adoring audience that helped put her husband in office.

Reactions have been mixed from the moment Jack Nicholson introduced her: Should she have done it? Is it too frivolous in these dire times for the first lady, bedecked in sequined splendor, to be participating in such self-congratulatory frivolity? Too much exposure? Too much … too much? As usual, the responses tend to break down along party lines.

We have such conflicting feelings about first wives in an era when women do it all, including, eventually, becoming president. We want our first lady to be first a lady — a delicate balance between enjoying one’s attractiveness without being too sexy. Michelle’s sleeveless toned arms have kept us riveted for four years.

We want our first ladies to be intelligent but not aggressively so. Supportive but not fawning. Politic but not political. We mostly want them to not embarrass us — and this will be the same for the first husband when he arrives.

To most of the country, Michelle has passed muster thus far. Her youthful health and fitness are inspiring — and she can grab and hold an audience as few others. She and the camera adore each other, though some of us miss her Jackie Kennedy period — the black Armani sheath with a double strand of pearls, hair brushed back to reveal her best feature — an arched, intelligent brow line. Why cover it up?

The answer may be as simple as sometimes a first lady just wants to have fun. For certain, Michelle Obama is the star of her own movie.