John Mayer and Katy Perry arriving to the restaurant "Little Door" in Los Angeles on September 4, 2012. Credit: Beverly News

Looks like John Mayer may not be "the one that got away" after all.

Despite Mayer breaking it off with Katy Perry in mid-August, the singer has rekindled his romance with Perry, 27. On September 1, the pair met up at L.A.'s FYF Fest. "They seemed back together," a witness tells Us Weekly of Mayer, 34, and Perry, whose divorce from Russell Brand was finalized in July. "She kept turning and whispering in his ear and kissing him."

Three days later, Mayer and Perry were photographed together following a dinner date at L.A. eatery Little Door.

Though their recent PDA may indicate otherwise, the duo seem intent on keeping their budding romance -- which Us first reported in June -- casual.

Says a pal of the "Teenage Dream" singer: "She told him she just wants to have fun."

For his part, Mayer -- whose exes include Jennifer Love Hewitt, Jessica Simpson and Jennifer Aniston -- is still clearly smitten with Perry. "John has always thought Katy was really sexy," a Mayer pal tells Us. "He loves curvy girls."