Why is my ferrets poop yellow?

[visaohburn]

My ferret Taz's poop is kinda a yellow color and slightly liquidy. I haven't changed his food or anything like that and my other two ferrets are fine. Other then his poop color there's nothing really wrong with him as far as I can tell. He's fur is normal and he's just as active as normal. I'm just afraid it could be ECE. Do you think I should be worried and bring him to the vet or just relax b/c he's fine???
Oh and he just let out a little cough. Is that ok?