I copied the first paragraph of http://www.andrew.cmu.edu/user/dhuston/quiz01.pdf (a file generated who knows where). I pasted it into Kile (v. 1.9.3, kile.sourceforge.net), where I found that the 'fi' part of the word 'field' on the beginning of the third line was registering as a single character. Using the text selector in evince yields the same result (selecting 'fi' as a single character).

I was able to reproduce the issue using Kile. http://www.andrew.cmu.edu/user/dhuston/quiz_1_redo.tex is a LaTeX source file, from which I compiled http://www.andrew.cmu.edu/user/dhuston/quiz_1_redo.pdf. The same problem appears - 'fi' in 'field' in the source is rendered as a single character in evince.