Hi Mate, This is the same problem I had on mine. Basically, although you havent done enough miles to warrant its next service, the car might be approaching two years old. By that I mean not two years old since it was registered, but two years old since the car was built and the electronics activated.
It was two years for me as I have a 1.6 Petrol, but the time interval might be shorter for diesels.
So, if your actual
level is OK then I reckon its just a reset that required to get rid of the annoying message.
Im sure someone will qualify what I just said...or if required correct me.