Seems like things are really beginning to heat up again between these two.
The two were seen kissing and dancing, with one source saying, "They seem to be back together."
An eyewitness who spotted the couple together said, "The two showed up around 10:45 p.m. through the back entrance with a group of friends and were holding hands at different points throughout the night."
In fact, one witness saw Zac lean in to kiss Vanessa, but she pushed him away as soon as she spotted someone snapping away on their cellphone camera.
Guess these two just can't stay away from each other!
[Image via WENN.]