I think the AI is detecting our bow equip, and aim direction. I noticed this way back when I first started playing. Random direction changes when the enemy is agitated is fine and looks pretty random to me, but I've more than a number of times notice a behavior/movement change once I raised my bow. Each deer, greyL or greyD I shoot has never seen me or my bow befor yet they occasionally react differently when I bring out the bow. Nothing major just enough to frustrated and eat through our arrows. LOL