Barring any leaks or major screwups my guess would be that your car was underfilled from the start. Seems that the fancy electronic 'dipstick' is confusing even for dealership personnel.
After my initial service the oil was reading a little low - put in a half quart and it was fine. Let the dealer know I did not appreciate spending five bucks a quart only to use it immediately after a scheduled service because THEY underfilled.
Could be the specs tell them to put in a very specific amount of oil which under some circumstances is not enough? Just seems like BMW makes this way more complicated than it has to be...