That could have very well been the case, Chris, although I didn't notice her move until after the arrow had hit.  It very easily could have happened quicker than I was able to perseve, though.
You're also probably on to something, Pat.  I did try to pick a spot as small as possible, but I did notice on the second attempt that I had a harder time focusing on as small a spot as before.
I shoot instinctive-ish, Pearl.  I do notice the arrow, but mainly use it to make sure my alignment is correct.  I very well could have second guessed, though.
It's all good, though.  It was a clean miss, no wounded deer wondering around out there, and I feel like I did the little things right in preparation for the shot.  My confidence isn't rattled, and I think if I get another shot I'll make good on it.  This would have been my first ever bow kill, which would have made it special, but then again now I get that chance again.