Any dust that gets into the nose is likely to get trapped between the many lens elements behind it. In particular, if the rear element is fixed then at least the lenses I own look pretty tight back there.
Some lenses do have moving rear elements. Might allow more dust through but I agree with the others- don't worry - be happy! You got yourself a nice camera and lens - shoot it this weekend.
I want to rent your D4 for a half hour to shoot a joust