Well it does look like there was a bit of wind, maybe a stray microburst?
Have you checked to see if there was siesmic activity in your area around that time?
I'm just guessing here.
If you'll look at my pic, the rest is pretty sharp too, you can tell who everyone is and what they were wearing.
I'm not saying it's camera movement for sure, because I don't know exactly what it is. It just looks similar to camera movement.