Just took a flight at about 200 feet elevAtion, I was hovering and when I tried to move forward, obstacle avoidance kicked in and stopped me. I immediate did a 360 and pan up/down to see what was there. I saw nothing. It seemed I was being blocked from moving left completely. So I added some height, and still same thing. I got nervous about possible malfunction so I switched to sport mode and came home. When I got closer I noticed a bird following the drone aggressively, but it was small like a purple Martin or a mocking bird. Has anyone had a similar experience? I'm wondering if it was sensor malfunction, or if it could have detected birds? Detecting birds seems like a long shot to me.