Are you still experiencing unusual colored stool? I do not believe the fecal matter coloration is due in part by the supplement contents, but then again every individual is different! You have been the first to mention this while evaluating , I may think dietary factors maybe coming into play? It's crazy but there is a Bristol Stool system with 7 categories of physical composition and genrally 5 "coloration" categories of fecal matter. Many slight changes in diet can affect digestive processes, as your body adjusts to changes.
Generally when dealing with "green" Scheizes/bowels it has much to do with digestive and nutritional related factors. The interrelated and combined effects of both, generally contribute to food moving quickly(quicker than usual) within the large intestine. As a result, Bile(greenish hue) not having enough time to break down completely. It may have much to do with your daily Iron intake, hydration, and for some, green food coloring. Effects correlated to Iron are evident in individuals with high intake of green leafy vegetables, chlorophyll rich products, and Iron supplementation.
I've yet to witness this while supplementing . Many years ago while taking an injury related break and wanting to stay healthy during the down time, I decided to incorporate a lot of spinach into my diet, both to stay lean and acquire my targeted mineral intake. I experienced similar, green logs, during this period. The effects were more pronounced when my hydration game was not , which I always stay on top of when training on a regular basis.