Over here in Austria they are pretty paranoid whether or not a car has had all of its service history done at the dealership and has the corresponding dealer stamps. Yes, as somebody earlier mentioned, if its under guarantee then quite, let them do it but thereafter what's the point if you know what you are doing and can back up your work with receipts and a log etc.
I recently sold my XK Jag which till I owned it was always serviced by jaguar, then I started doing it myself, so when I went to sell it I had four people come to look at it and each an everyone wanted to see the service history stamps, which the last two were missing. I showed them receipts and logged what I had done in a separate booklet, none of them were impressed as its so unusual over here. I eventually told the last guy who came to view it that I had worked as a mechanic for 3000 HP Swiss Funny car drag racing team and offered him as a reference, still he claimed that a Jaguar is something completely different. Anyway he bought it in the end, even with his wife moaning that the kids won't fit in the back… good luck with that. So all that being said, my Z has just gone past the 3 year warranty this July and I've decided I will get one more service done at Nissan being as the 60K km is due and thereafter if I decide to keep it till the next is due, then I'll do i t myself again.