I cleaned up the stains with carpet cleaner the last time they appeared, so they are not bright enough to show up in a photo. But, if it happens again, I will try to post a picture. This is not the first time, so I'm sure it will. We don't know of anything that has been spilled. Fuzz did have to repair a leak behind the docking station wall, but I don't think he used anything yellow.
Thanks for the responses. I'll keep watching it.