wierd duck behavior

My Swedish Blue hen took up a very strange posture today. She was on land, she stretched her wings all the way out to either side and pushed down on them. It looked for all the world like she was trying to push out a huge egg. Her belly was soft with no lumps and her vent was clean. She had also already laid an egg today. Eating, drinking, vocalizing and moving around normally. I've had her for three years and never saw anything like this before in her or any of my other ducks. Any ideas?