Hi guys and Gals
As Simons says (no pun intended) this is a common problem. My advice is be patient. It is nothing to do with a faulty body computer, it is classed as a maladjustment of the brake switch, but you will find that the brake switch has been adjusted so that once your brakes "bed in" after about 1000 miles of driving the errors will stop occurring. Not a good solution, I know, but that is the way Alfa have designed it. Mine got the errors when I was either slowing down gradually with my foot lightly on the brake pedal for a long period of time or when I was holding the car, on the brakes at junctions, traffic lights etc, for several minutes.
Just see if the errors start to appear less frequently over the next couple of days, and that should put your mind at rest.