Is Brad Pitt treading on his ex’s turf? After a long day of Ocean’s Thirteen reshoots, the actor brought in his 43rd birthday December 18 with George Clooney, director Steven Soderbergh, producer Jerry Weintraub and other pals at West Hollywood eatery Il Sole – a favorite haunt of Jennifer Aniston’s.

But at his birthday dinner, Pitt didn’t seem to have his ex on his mind. “It was a really mellow affair,” a source tells Us of the 20-person soiree, which took place in the private Wine Room.

Not in attendance? Pitt’s girlfriend, Angelina Jolie and their three children, Maddox, 5, Zahara, 2, and Shiloh, 7 months. Maybe it was the grub that kept Jolie away (a source says she vowed years ago never to come back after Il Sole refused to make her a special dish).

As for the birthday boy, an eyewitness says, “He looked tired but happy.”