I don't recall Apple shipments from China coming from Zhengzhou. They've usually been from Shenzhen (China's Silicon Valley). Both cities are megalopolises, but Shenzhen is more active.
Cargo planes don't always run on a schedule. Making the assumption that the next stop would be Anchorage, there are usually several cargo flights from Zhengzhou. The next one is typically Sunday, CST.
Of course, UPS could just fly their own airplane into Zhengzhou, but there is no indication they have ever gone there.