It seems that Nikon quietly increased the prices of many (all?) Nikkor lenses in the US at the end of June – here are few examples sent by a reader who actually tracks the prices over time (based on B&H listings):
Nikkor AF line:
Nikkor AF-S line:
Nikkor DX line:
Nikkor PC-E (tilt-shift) models:
It could also be that a long term Nikon lens discount ended and the prices just went back to the original MSRP, but the fact is that you will have to now pay more if you want to buy a new Nikkor lens with US warranty.