The former lovers, who celebrated the release of mutual HSMco-star Ashley Tisdale's Sharpay's Fabulous Adventures DVD, were ultra comfortable with each other.
"Zac and Vanessa definitely seemed comfortable around each other," an observer told Us. "They didn't seem affectionate or romantic at all, but they were totally relaxed and friendly."
Another source added: "They both came out to support Ashley. They knew they would both be there and were fine with it. They really are still friends."
Apparently, it was one big High School Musical cheerful get together with lots of the hit show's stars -- and likely lots of excited shrieking and hugs.
"It was like a High School Musical reunion!" says the first observer.
Oh, geez. At least Vanessa and Zac are acting more mature than their cross-eyed lovers fromHSM presumably would have.