Mobile speed camera.... grrrr?

I was driving along behind a car (in a 60mph area) who was doing 45-50 mph,so as a few cars behind me had overtaken me and the car in front of me,i decided to follow. As I overtook my speed went up to just under 70 mph,but as soon as i pulled back in i slowed back to 60,i then noticed a mobile speed camera parked about a mile up the road with the camera facing me and by the time i ped it i was doing 50 mph. i was only over the speed limit while overtaking,would i have been caught or what will happen if anything?