According to Perezhilton.com, they were seen eating at a restaurant in the town of Wilmington two nights in a row, before heading back to their hotel, where they shared a room.
Another source told the website they had been at a party for cast and crew on Saturday, and the on/off couple were “inseparable." It was also there where they were caught smooching in a corner.
The couple started dating in 2005 after meeting on the set of High School Musical, in which Zac, 23, played basketball team captain Troy Bolton, while 22-year-old Vanessa portrayed bookish Gabriella Montez.
They broke up in December 2010, citing their respective work commitments as the reason, but friends said at the time they felt would always get back together.
A source said at the time: "They realize that they both can trust each other, and there will be a bond between them forever.
“Career demands, distance and wanting to enjoy being single are the main reasons for the break-up. I'd be shocked if they don't get back together someday."