How soft of is this particular blue cheese? If it's a fairly hard one (more like cheddar), I'd keep it. If it's a soft one, like Brie, I'd toss it. Bacteria (not just mold) grows really, really well in soft cheese. Do you know what that particular blue cheese tastes like when you know it is ok? If you do know, then I'd taste a small part of the suspect cheese and see if it tastes completely normal. If it tastes at all different than normal, even if it tastes different in a good way, pitch it. This is the voice of experience: I once got very sick from eating a soft cheese that had been sitting out for about three hours. It tasted different than normal, but it was much, much better than normal. It had a fabulous, strong taste. Well, I and everyone else who ate it spent the next couple days vomiting with awful stomach cramps.