What was it?

[fido]

i was driving up the A3 from guildford, a few minutes before the M25 turn off.

passing an erected board about 20ft tall with yellow and orange stripes, and noticed a roadworks / police car parked in front of it. it was only after i passed it that i decided to slow down a tad, at which point i was flashed what seems like three or four times. i then passed a patrol vehicle about a mile ahead, with two officers walking outside the car.
have i been nabbed by a 'safety' device?

yours worried (for the next 14 days...)