Personally mate i'd say i'm 99% certain that the camera couldnt have got you from that far away. I don't think they can see the white lines on your side of the road as the angles are all wrong and it needs the white lines to work out your speed.

If there was cars on the otherside of the road I should think it was one of those that set it off. And you're in the clear. All fingers crossed mate I reckon you'll be fine. (touch wood)