Hello! I recently got my first DSLR which is a Nikon D500 and I paired it with a Sigma 150-600 C. I got the D500 used, but it looks brand new, and only has a shutter count of around 3000. The only issue I have with it is that when looking through the viewfinder I can notice some dust around it. Does this usually happen with cameras? Could this easily be cleaned by a camera shop?