I can picture the scerio exactly, and I had the exact same shot happen to me with a doequite a fewyears back. And it left me with a felling of "Whoa, what just happened", everything was executed correctly. Unfortunately I didn't find the animal either. I didn't have any lung blood, only muscle blood. I don't believe you were at fault at all. It was just one of those things that happen sometimes when you are shooting a living creatures.
In this case I gave this animal 6 hours and had I caught the lungs in any way I firmly believe this animal would have been expired.
Actually, if nothing elseis hit,it is possible for adeerto survive a one lung hit.