I just collected an egg from the coop that has a brown-red splotch on the shell at one end. It does not appear to wash off. Is this anything to worry about? My girls are around 6 months now. The egg also changed color where I handled it which was rather weird! Not sure whose it is - we have Orpington, Australorp and Wyandotte as possibles. They free range for a good part of the day, eat lots of leafy greens, and mostly ignore their crumbles - they have starter/grower crumbles and separate oyster shells as we also have a cockerel. They are also very fond of scratch and treats . Darker egg is after rinsing. Many thanks!