Stick with it. Don't get too antsy about releasing the arrow. It sounds like you rushedthe shotby releasing an arrow on a deer you didn't really have a shot on.
Relax, take a breath, pick a spot and wait for the deer to come clear before releasing.
You are probably right... I am pretty well relaxed when I get ready, I think the unexpected bleat by my buddy threw me off as well as the deer!
At least these things are a great learning experience for next time!