Recently (past 3-4 days, could be wrong though) I've been doing alot of hunting and during which I've been killing alot of animals... anyways, when it comes to killing a deer (I use a sling mostly) if I don't kill it with one shot it'll either run at me or take off. When it does run at me it tends to run up to me and do some sort of strange jittery spaztastic dance, grinding up on my character and not attacking (lowers my aim bar too like its running around). I usually have to walk in various directions to make it stop and finally hit me.
tl;dr Deer sort of dance in front of me when aggro'd. Unless animal affection has been added and I'm being an idiot this is a bug.