by James Roberts.
Scott,
I'm having the same glitch under Moodle 2.4. Curiously, I get all 4 variants within a single course: empty box, green check mark, blue check mark and red cross. I may be wrong but it may be related to when one changes the "Grade to pass" setting. It seems that if you change/set this after a student has answered the quiz, the check mark is blue (not green).