I agree with what a previous poster said and would advise you to tell your insurance company so they are forewarned.
A few years ago, my mum was driving up our road and had to pull close to the left as an ambulance was coming down the road. As she drove past, she managed to scrape our neighbour's parked car. She got out and checked the damage, it was just a tiny scratch with a bit of our car's paint left on similar to what happened to you. She exchanged details and thought that would be the end of it. A few weeks later, she got a letter through from the neighbour's insurance company that had been mistakenly sent to her detailing his claims. He was claiming for EVERYTHING, saying that he had to pay to have the car looked at by mechanics at a garage, the chassis was damaged, just a load of crap. She even got a court summons letter which was ridiculous. You can't trust other drivers, they're not honest. Luckily, she told her insurance company and they sorted it out for her.
It puts you off driving sometimes! My mum hasn't really driven since and I'm sure it's because of this. It's a total joke what people try and get away with.