There is a lengthy thread on the MyEclipse forum (
http://myeclipseide.com/PNphpBB2-viewtopic-t-19186.html) describing problems with MyEclipse changing fonts/attributes for some file types.
I have seen these "micro" fonts on .SQL files as well as ant Build.xml files.
Edit: To correct this behavior, I go into the Preferences and change the "Fixed Font" to something besides my default, hit "Apply", and then set back to my preferred font and hit "Apply" again. This fixes the font, but, it will revert back at some point until MyEclipse addresses this bug.