Was the itsy-bitsy bikini Jennifer Aniston wore during her recent snuggle-bunny-filled Miami weekend with John Mayer the only thing with strings attached?

The New York Post says the feather-coiffed crooner was spied partying at Manhattan hot spot 1Oak Friday night with Maroon 5 front man Adam Levine -- and a fair-haired female.

A spy claims Mayer "was all over some blond girl" and even requested the DJ play some R. Kelly songs so he and Levine could "dance with our girls."

And it's apparently stories like this that have Aniston's pals concerned that she's spelling romance M-A-Y-E-R.

"It's not that we don't like John, it's just that he does have that reputation as something of a serial dater who never sticks with one woman very long," an insider explains to the Chicago Sun-Times. "It wouldn't be a big deal if this was just a casual thing. But Jen isn't into 'casual' ... She wants a real, solid, genuine relationship."

That's not to say Mayer doesn't have gentlemanlike qualities.

"He's very old-fashioned about a woman -- opening doors, standing when a woman comes to the table ... things like that," a Mayer source pipes in to the paper. "Even when it comes to bringing or sending flowers. John doesn't just grab a bunch of roses. No, he will pick out individual flowers and create his own personalized bouquets. I've heard him spend 45 minutes on the phone with a favorite florist, methodically describing exactly what he wants."

The self-reflective singer, who is said to have had several sprays delivered to Jen's hotel room during their fun-in-the-sun weekend, didn't avoid the bronzed, swimsuit-clad elephant in the room at Monday night's Costume Institute gala in New York.

"Listen, this is not a scandal, this is not an issue, this is not a problem, this needs no spin control," he declared to "Entertainment Tonight" of the snaps of him soaking up some rays with the actress. "This is me living my life ..."

He downplays that the shots of the two cozying up were taken by a paparazzo with "a really powerful lens, and I don't fault him, I don't fault anybody. I don't fault you, I don't fault this or that."

Besides, he points out, "There are much worse problems in the world. Everything's cool!"

As for the pictures themselves, which showed the messy-maned duo, who enjoyed a romantic weekend of eating, hanging out and grocery shopping, lying side-by-side on a chaise, the troubadour gives them "double thumbs up."

When he saw the photo spread, "I looked at it and I said, 'That's about right,'" shrugged the mellow Mayer to the AP. "What am I going to say, 'That's not me'? ... You carry on and you enjoy yourself and you continue to live with dignity and everyone has fun."

And by "dignity," he apparently means "cheekiness," because after ditching his monkey suit following the Costume Institute fete, he slipped on a T-shirt reading "Mr. D****bag," an epithet he then proceeded to cross out with a Sharpie and change to "Mr. Badass."

But despite his message tee, Mayer did show off his sweet side later that night.

According to the New York Post, he performed "Happy Birthday" at Bungalow 8 for fellow pretty boys George Clooney and David Beckham, who recently turned 47 and 33, respectively.

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