Had a grape soda last night. This am 1/2 of bowel movement was ok. The other 1/2 was dark green. Is that normal? Should I worry?

Green Stool. If the stool was loose, the reason for green stool could be too rapid a transit time in the gut. Eating green leafy vegetables can lead to green stool. Green cabbage, lettuce, peas, cabbage, spinach, broccoli, green salad, green leaves, celery and green beans as well as food that contains green food coloring can lead to green stool. See you take bisacodyl - that could ^ transit time.