How close was he when you grunted at him? If he was fairly close he was standing there looking for the "deer" that made the noise. When he saw nothing he probably knew something wasn't right and decided to get out of Dodge. I try not to call to deer when they are within bow range unless I have a decoy out or it is very thick cover. When deer don't see the source of the sound they tend to get a little nervous. Grunting at them to stop them for a shot is the exception though. As for future encounters I would not give up hope. He may be a little wiser next time so try a doe decoy to see if that works.Keep using the can call. Rut must be kicking in Alabama.