Sometimes, you will see this with simple stomach upset. It usually means that you are seeing bile mixed in with the fecal matter. This is not really a danger sign as long as it resolves itself within a reasonable amount of time. The body will overproduce bile and pass it through the stool for simple reasons like GI upset and even if she just eats something strange.
I would keep an eye on it but I would not be too concerned at this point.
Let me know if you still have questions.