In reply to Rick Asher: If it's not affecting images (it shouldn't at f/<16), I wouldn't worry about it. Normally there is quite some tolerance for dust specks, especially near the front end of the lens.
However, if the inside of the lens looks like this:
http://www.lensrentals.com/blog/2013/05/how-to-ruin-your-gear-in-5-minutes-...
(scroll down, last picture)
I'd start to worry.