I have not read anyone having this bug so here goes. I was walking south of Goodsprings and came across a gecko. I attacked it first. I used a lot of ammo on it until I realized I was not damaging it. It did it's little attack thing, standing on it hinds legs, mouth open. I got closer, point blank range. Gecko is still attacking but stationary. Mouth still open. I unloaded lots of ammo and still no damage to me or it. I walked away and the gecko was still upset but not moving from where I first started shooting at it. I reverted to a previous save to avoid any issues and to get back the ammo that I wasted. Definitely not a game-killer bug and I got to get a close look at the little bugger when it is angry.