Well honestly spiker, you probably did the wrong thing in this situation, in my opinion. If a buck is 25 yds away, I'll never grunt or call or anything. That's when I'm absolutely quiet. You're exactly right, he heard the grunt and calls but saw nothing. Right then he knew something was wrong. Deer hear just about as well as humans, but they hear higher pitches better than us. They can locate where the sound is coming from just like humans can too. If it was really thick where he was at, I MIGHT HAVE grunted really softly, a time or two, and made the sound go behind me. If you're using a can bleat, those things only tend to have one volume. LOUD. I hope you get another encounter with him soon! Try what I said, you may just bag a buck!
...and on that day when my strength is failing, the end draws near and my times has come, still my soul will sing Your praise unending, ten thousand years and then forevermore!