The panel fell from the roof in the central atrium, above the escalators, but missed shoppers.
A health and safety investigation is now underway but the shopping centre is open as normal.
A number of kiosks close to where the panel fell are not trading and the escalator is out of action.
A shopping centre spokesman said: "A piece of glass has fallen from the roof of the central atrium close to the escalator area but the most important thing is that nobody was injured.
"The centre is open as normal apart from some kiosks which are not trading because of their location near the escalator.
"Health and Safety are there as a matter of course."