"Oil level above maximum" - how accurate is the electronic dipstick?

[RockDriver]

So a dealer replaced the oil and filter on an F15 30D I bought yesterday (I know, I'm doomed). When I drove back home, I ran the "Measure engine oil level" feature on the iDrive and it came out with "Oil level above maximum" warning. I've checked the physical dipstick and it looked about at max, although it was dark and I'm gonna check again in the morning just to be sure.

Thing is, I saw with my own eyes the guy bring 7 liters of oil (one 5 liter bottle and two 1 liter) and pour 6.5 liters in, leaving about half of 1 liter bottle. So that's exactly how much N57 engine needs, right? The margin of error in this case could have been some 200 ml at maximum.

How accurate is this electronic dipstick? Is there any cause for concern in this situation?