I had the same problem, and I finally found a workaround.
First, you need to install PDFCreator on your computer (http://sourceforge.net/projects/pdfcreator/
). Then, open the lesson notes PDF in Adobe Reader, click on Print and choose the PDF printer. The obtained file is the same as the first one, except that it now works on the iPhone!
(I guess that the fonts are embedded differently that way)