Mine is sometimes yellow, sometimes green and can be every shade of orange/brown. I think it depends on what I eat. I suppose other things could factor in too. I would casually mention it to your doctor, but I'm guessing it's nothing serious.
If I may share a somewhat gross story...I was at a semi-formal function the other day & watermelon was served. Well, I didn't want to just spit the seeds out on my plate (very unladylike), so I swallowed them. The next day or so I had black spotted stool and it scared me at first, then I figured out what it was!
I told you it was gross!<img src="i/expressions/face-icon-small-wink.gif" border="0">