Look it happens..throw away the vow....your only concern should be handling him with that rifle....
Let him handle the deer.
Just him saying he hit it is awesome, next time believe him. He saw the shot through the scope, which is real hard to teach, so your doing good.
As soon as i saw the 30 yard part of your story, i shook my head. 30 yards is never the distance to quit looking, ( i know i know unless its dead)..
Everytime we go get the dog, we were just 20-40 yards from findin the deer..just how it goes i guess