In the movie [Predator](https://en.wikipedia.org/wiki/Predator_(film))
 (1987), near the climax, when the Predator finds Arnold, it did not try to kill him immediately. Instead, it goes near him and checks his head and removes its helmet (I am assuming that it would be its helmet). 

**Why did it not kill Arnold immediately as it killed everybody else?** Did checking Arnold's head mean something?