This normally wouldn't be a big deal, but this was also the same week that Jen gave that explosive interview to Vanity Fair in which she broke her silence about the infamous nanny, Christine Ouzounian, and called the "Batman v Superman: Dawn of Justice" star the "love of my life."
The two reportedly remained civil, but Ben didn't stay long after Jen arrived. He actually left the same time as Charlize Theron, whom he costar in 2000's "Reindeer Games" with.
Jen and Ben actually had been together the day before, reuniting to celebrate their son Samuel's fourth birthday.
There, the exes put on a united front for Samuel's superhero-themed birthday party, which is of course in keeping with Ben's upcoming and highly-anticipated role as Batman.
A source told Us Weekly that Ben attended the bash at Jen's house and there were, "lots of moms, dads and siblings." Kate Hudson's kids came with the nanny. Reese Witherspoon's son Tennessee, who was dressed as Captain America, was one of the many party goers, and so was Victor Garber, who starred with Jen on "Alias."
Ben and Jen have been the poster children of separation civility. Jen, however, shocked the celebrity news world last week when she gave that revealing interview to Vanity Fair.
She didn't shy away from anything, including their children's nanny, whom Ben denied cheating on Jen with.
"Let me just tell you something. We had been separated for months before I ever heard about the nanny," she said. "She had nothing to do with our decision to divorce. She was not a part of the equation. Bad judgment? Yes. It's not great for your kids for [a nanny] to disappear from their lives. I have had to have conversations about the meaning of 'scandal' [with her children]."
Ben and Jen have three children together: Violet, Seraphina and Sam.
Despite the hurt from the split, Jen says she would do it all over again with Ben.
"I didn't marry the big fat movie star; I married him," she said. "And I would go back and remake that decision. I ran down the beach to him, and I would again. You can't have these three babies and so much of what we had. He's the love of my life ... He's just a complicated guy. I always say, 'When his sun shines on you, you feel it.' But when the sun is shining elsewhere, it's cold. He can cast quite a shadow."