Have you let Nikon know about your problem/issue?

Then you've been lucky. There are others who have sent their cameras in, and ended up not getting the problem fixed.

I don't like your theory about the sensor dust issue coming up because there's plastic in the body. Many others have had DSLRs with far more plastic (D90 for example) that didn't have dust problems. I had a Sony a580 for about two years before I got the D600, and never had as much dust on the sensor as my D600 did after a few thousand shots. Like other entry level cameras, the Sony a580 is built almost completely with plastic (excluding the electronics/glass). I've put my a580 through far worse than what my new D600 has been through, including rain and nasty drops. Plastic doesn't cause dust, and as far as I'm concerned, plastic in a camera just means lighter weight, lighter cost, and more impact resistance.

"Low experience novice photographers"...hmm...those are usually the ones bragging about shiny all-metal gear instead of taking pictures, right?