If you are using Lion, Apple Preview has a known issue with PDFs and fonts (heck, and transparencies, and ...). What the heck was before Lion? Snow Leopard? In any case, it too had issues. I know that as late as early 2011, Apple Preview could only accurately and consistently handle PDFs made to Acrobat 4 standards...Pretty lame. The Adobe forums (AI and ID) have many threads about Apple Preview and Adobe products.

Take care, Mike