I am new to raising chickens. I have had my first group of chickens for almost a week now. They are young pullets, around 5 weeks old. One of them is a Black Copper Maran that is definitely a rooster. He is a very sweet boy, one of the two most friendly in the group, and he is already VERY pretty. Today as I was putting them back in their coop for the night, I noticed that he has a large mass on his chest, about the size of a golf ball, maybe bigger, and perfectly round and somewhat hard. Would this just be a full crop, or do I need to worry? He doesn't seem to be in any pain, and before bed was running around, eating like crazy. Any advice would be greatly appreciated by this chicken noob. Thanks!!