Service does not like to top it off because....
Your level is completely OK, about 1/2 liter low (or above the minimum, depends on if you are a half empty or half full kind of guy), so you don't need to do anything. The reason that most dealers only fill to this level is that if they even slightly overfill, or if the level sensor changes a bit and now indicates an overfill, they have to drain all the oil and start over again. If you have checked your oil level sensor much you will notice that it move around a fair bit from time to time, so the dealers are now very wary about getting near the top lest the reading go over the top and throw an error message (so they have to drain it).
My issue is that the car does burn some oil (about a liter every 8000 miles) and the oil is very hard to find (not to mention being insanely expensive) so I don't want to be stuck 200 miles from anywhere that I can buy the oil when I am low on oil. I always ask the dealer to give me an extra quart of oil to put in the trunk so that I can top off when needed. So far that extra quart has been enough to get me to the next oil change, even though the car came back from the dealer with 1/2 liter below full.