What happened? Bird strike from behind?

Just cruising in manual mode, no trees or branches around. Neo 1 flips upward looking towards the sky. I'm mediocre at manual mode and not able to think on my feet enough to figure out which way to tilt it back to something near level. Looking at the sky (and it being my last battery as it got dark) makes it hard to orient. I attempt to flip to sport mode so it will catch itself, but too late.

I was able to recover, but it almost went into the yard two neighbors over and I don't want to be crashing off my property. I think this has happened once before a couple months ago when I got the drone - unexpected flip up.

Only thing I can think of is bird or bat strike from behind. Bug getting in the props? That, or some weird software glitch. Any ideas?