Everyone makes mistakes, and as long as you learn from them and make an effort not to repeat them, then there is no problems. My Father is probably the best, most ethical hunter i know, and instilled in me a 1 shot 1 kill philosopy. Even he has gut shot a deer, I think nearly everyone has done something and later said, "What the hell was i thinking?" Some cases people are lucky and nothing terribly bad happens, other cases the deer runs off. Thats life, don't let this bother you too much, as long as you learn from it.