Welcome to the club. I did a special image showing Every Little Problem in my system. Turns out I had front element dust, rear element dust, sensor stains, and a hair in there somewhere!
(click image for larger sizes)
Man, just think - If I would had never done all of the special editing to this pic to make all of the imperfections show up I never would have seen them! Imagine that!
But on a more serious note: it's going back for cleaning/repair as soon as my new-to-me K-10 gets here. The stains were really, really visible in stacked lens macro photography.