You just never know. My guess is he heard your draw, the slightest noise but it sounds like he was unsure of you. That is good for you. If he knew you were there he more than likely would have been snorting and yelling. Even if they do or don't I always in that case put out a couple of grunts or so just hoping it does make him unsure of what you were. He should be back. Nobody can tell you when but be ready next time and try to have your draw before he gets there.