ok, i know i need pics with it, but need to get my camera tomorow and ill post them then. But perhaps someone will know what i mean in its description, Half my flock (5 out of 10) have just started to get grey spots on the end of their tail feathers. it doest have any texture and doest wash off, it looks like its stained into the feather. any idea what this could be? should i be worried?