I've noted that my speedometer is reading 3-4 mph faster than my indicated speed on my GPS. Anyone else noted this discrepancy? If the speedo isn't tracking accurately, especially reading faster and putting miles on the odometer faster, this will make my warranty expire faster. At best it'll keep me from going over the posted speed limit, if I fix my speed, via the speedo, at the posted speed limit.
Assuming you have not done any aftermarket programming. A value difference between the speedometer and GPS is most likely a calibration issue, as opposed to a sensor problem.
I don't see any speed signal related technical service bulletins, but there are a whole bunch dealing with other software problems.
Definitely get it back to the BMW dealer and explain the condition. They may want to input the latest software just to be on the safe side.