Sounds like your bullet did the job and so did you. Some deer are tougher than others and it doesn't always have to be about size. Lung shots are funny they can drop a deer and some just drown in the blood as the minutes tick by. Cutting through both sholders usually is a sure thing for dropping a deer. But that deer proved us wrong on that thought. What kind of bullet did you use. Did it mushroom did it go straight through with out a mushroom. You could ponder these questions all day long. Great that you got your deer and any deer recovered is a trophy.