what caused rainsford to believe zaroof knew he was hiding in the tree? do you think he was right?

Rainsford is on the low level of a tree. He watches Zaroff beneath him. Zaroff examines the trail and slowly lifts his head but stops short of Rainford's branch. He shakes his head, lights his cigarette and walks away. Obviously he knows where Rainsford is; he merely wants to prolong the hunt.