well I've been competitive shooting for so long I can't remember and won my share of 3D tournaments and I know I can place an arrow at 15 yards
Congratulations.
t-I'm a little confused as the body position of the deer from your post. You said said he came in, and when you whistled, he stoped turned and looked directly at you at 15 yards. But, I'm not sure if he was walking directly away from you, was directly facing you, was broadside, quartering away, or quartering to you when he stopped and turned to look. If he was broadside or quarting away, I would have shot at 15 yards even if he was looking at you. Any of the rest, and I would have let him passed. No matter what, you were not sure of the shot and let him go. That was a very ethical move on your part. So congrats no matter what.