I have seen this before and today a client asked why the "I"'s and the "l"'s looked odd. I opened the file and you see these 2 letters much bolder than everything else...I also noticed if you zoom in they look correct. Any reason for this?
This is a rendering bug with Adobe Acrobat/Reader. It only display it as a thicker stroke but it prints fine. If you open the same file on a Mac via the "Preview" application, the problem goes away.
By turning OFF "Enhance thin lines" in Adobe Reader's preference, you can eliminate the display problem. But since the files can be distributed to other people over the internet, this may not be an option!
Oh, and it only happens when you convert your font to outlines before saving as the PDF file!