don't check mine often enuf but did the other day and it was way past the full mark, probably about 3/4"!
i'll probably drop the oil @ 15,000km and change it and the filter myself and attempt to measure how much oil comes out.
i reckon it was just sercived by an apprentice having a bad day.
oh well, that's what warranty is for if anything goes wrong.
as for ur 5mm past i wouldn't be too concerned, it really doesn't take much to read overfull. just something to try, before you dip it again, clean the dipstick vigorously with a rough fabric, have had a couple of occasions where a silicone like build up can adhere to the dipstick and it couses oil to travel up the stick, sounds crazy i know but i'm not pullin ur chain!
another thing is, try turning dipstick over and redipping, in some applications or at certain oil temps the angle that the dipstick enters the supme can give you inaccurate readings.