I noticed a slight limp or uncomfortable ness in one of my hens today. She was standing on her "good foot" and when walking was walking quickly with the hurt one like a human would. She also stumbled over any obstacles like she's was hurting. Her foot looks totaly fine, had a lil Poo on it witch she lovingly got all over my jacket but other than that no cuts or swelling. I did notice one foot was warm and the hurt one was cold and she kept the foot that she was limping on closed up. Maybe she just stepped in a really cold rain puddle?
She may have bruised herself flying down from her roost or any number of possibilities. Since there is no significant injury, I would just keep a close eye on her if she were mine.