Recently had an intermitent grinding noise coming from front offside of my Mii. As the car is only 3 months old was a bit concerned. I took it in to the local dealer who appeared to recognise the problem even before looking at the car. It turned out to be a stone trapped between the backplate and disc on the osf brake. I was disappointed to be told it was a chargeable job and not covered under the warranty. I just wonder is it a common problem and am I to expect it to happen again?Just thought it was odd the garage suggested a stone was the problem as if it was a common fault.