Nosema?

Went out to the hive this past weekend and saw some "spotting" on the outside of the hive. Nothing like some of the pictures with long streaks of waste. I understand that this is obviously hard to quantitate in a yes/no answer but I'm curious, if I should assume with any waste spotting that my girls might have Nosema? Guess I can see if I can get my hands on a microscope and sacrifice one to see if there are spores in the gut.

Thanks,
Chris