mnshedhunter, I was indeed still kneeling when the shot went down. It took he buck roughly 25 minutes to make his way from where he first came out to where I shot him. The entire time he was periodically checking out my direction as he knew I was there. Also I had pulled a camera tripod off of my backpack when I first kneeled down. I then had set it up and was doing my best to get some video of him.
Because of where I was set up I didn't always have the clearest of lanes to get him in focus, so when he'd put his head down to graze I'd adjust the camera. This little cat and mouse game continued and I think it was the camera movement that drew him into range as it was impossible for me to get him zoomed in and in focus without him spotting movement some of the time.
I think he was trying to get downwind of me but the last time I moved the camera, when he was at 70-80 yards, he decided the had had enough and began to circle back in the direction he came. He wasn't in a hurry though and when he got turned broadside and stopped I simply raised my gun, rest it against a small polar tree that was in front of me
and belched out a cloud of smoke. He ran about 100 yards, I watched him fall.