I bought mine from a fellow Nikonian here a while ago. I noticed some spots and tried to remove them with my Giotto rocket blower, but ended up using the sensor cleaning swabs. Had to do it a few times to get the spots off, it may have been stubborn dust or a little oil and dust.
I change my lenses a lot and am very careful, but now I do a test shot once and a while and the blower has been able to remove the dust so far.
Don't be afraid to clean your sensor, it is easy and works well. Just follow the directions and take your time. There is a good video by Moose Peterson on cleaning, do a web search.
By the way, my eyes are not that great, but I don't really see the spots in your images.