I really like Indigo Vapor's Oohrah and the last time I went to refill my Protank II, I noticed that the juice in the tank was much darker than what was in the bottle. Is this because of the heat from the atomizer? Or, is it impurities in the juice? (I remember seeing that somewhere) This is my current ADV and I'd hate to find out there's something wrong with it. I've used other juice from Indigo that didn't discolor like this one is. Anybody else know what's going on?