Yeast?
Green??
Whenever I get yeasty cheese, it smells yeasty, and develops white patches. Cheddar, being faintly sweet, is the most common victim. Doesn't seem to be anything wrong with eating it, it's just less... cheddary.
Sour, socky flavors are often found here, which would be evidence of lactobacillus, probably from the skin.
Hmm. I wonder if such cultures could be cut off and grown into a cheesy sourdough starter, or something. Ehhh...
Tim