I'm a first time ferret parent and although I've been doing quite a lot of research on this, maybe someone could tell me what's wrong.

A few weeks ago I got a female ferret, Athena. She just turned 5 months old. Up until now, she's been very healthy. Just today I noticed that her poop is green and slimy, almost even stringy. She is eating quite well, though, and drinking plenty of water. And the food I buy her has no artificial coloring, and I dont give her tap water, only filtered. She is still active and playful, and isn't acting out of the ordinary. When she's out of her cage, which is quite often, I watch her closely to make sure she doesn't accidentally eat anything, although I had to go out of town for a day and leave her in the care of my brother and friends. However, they didn't say that anything was out of the ordinary.

This is the first time this has happened, should I continue to watch her, see if there are any changes? Should I take her to the vet? Change food? Or give her some ferret lax? Or something else?