Did you scroll down to the pics for abnormal poos toward the bottom of the page where it shows pretty much all red? Does it look like or similar to that?
If so it could (not an expert here just suggesting) be coccidiosis. In which case you will want to get them on a treatment of Corid...
Here is a link to a poop chart that may help you pin point if it is a problem or not.
http://chat.allotment-garden.org/index.php?topic=17568.0
If/when you have further questions please feel free to ask.