He starts running. Makes it half a block, all the way to the park. Stops. He tilts his head to the side curiously and then glances around at his surroundings. The hair on the back of his neck stands up.
People are milling about, some on benches, others walking leisurely without any apparent motives. On one bench there's an old and a girl. Baggy shirt. He passes her over quickly. She can't possibly be the source of the sudden anxiety that overcame him.
He sees nothing particularly out of the ordinary and so, brushes off the odd feeling he has. Starts jogging again. He soon has regained a steady pace and has forgotten about the park.
Later though, the girl plays a part in his dreams. He wakes up, confused.