Jen Aniston Helps John Mayer Celebrate His 31st

The couple appears to be back on as Jen celebrates the singer's 31st birthday at an exclusive cigar bar

Here we go again...survey says Jennifer Aniston and John Mayer are back on.

In the past week, the two were spotted at a concert in Boston and on a dinner date here in Hollywood.

And just last night, Jen was by John's side as he celebrated his 31st birthday at the Grand Havana Room.

No, that's not in Cuba. It's actually a members-only cigar bar in Beverly Hills.

The two reportedly chilled at an outdoor patio for a few hours. At one point, John even "affectionately stroked Jen's hair ".

Ooh, petting in public? Must be serious.

But is rekindling her romance with John "The Player" Mayer really wise...especially after he blabbed to all his pap buds after their breakup? Sound off below!