I also notice that when you enlarge the pdf (the http://www.whitehouse.gov/sites/default/files/rss_viewer/birth-certificate-long-form.pdf link) that after 11 clicks, you lose the green “security” background and also various parts of the text and markings. I don’t really know how PDF works, but it seems strange to me. For example, why do you lose the X marked by M.D. and various parts of the signatures?
The pdf format has limited resolution. The fact things go away when you zoom in too far is not surprising, nor evidence of anything amiss.