A few of my girls lay eggs with slight vertical ridges. You can barely feel them and only see them in good light. I got one today that is more obvious so i snapped a pic. This seems to happen after cold snaps, so I pondered if lack of water causes this(I break the ice up often but freezing water does limit them more). There has been some stress due to noise(clearing a wood pile near coop). These girls are from mcmurray, lay daily, and no one is sick. Should I be worried or is this a common egg issue on occasion? Any advice?