He then followed her out of the shop into the food court where she had gone to seek refuge.
The teen lost sight of the man near one of the food outlets. Police believe he may have been masturbating as he walked around the shopping centre on McDonalds Road.
They have released images and CCTV footage of a man they wish to speak to.
He is described as being of a slim build, with short dark hair and stubble on his face.
He was wearing a dark top and light grey pants, and he was carrying a plastic bag, possibly containing a bottle of milk.
Anyone with any information is urged to contact Crime Stoppers on 1800 333 000