I would wait and see as you just got her. This might be due to water or food change or stress. Or as is typical of a baby animal she may have intestinal parasites that will need some medication to take care of.
Make sure she isn't chewing on any toxic houseplants or getting into something she shouldn't.
Kittens do tend to explore with their mouths.
If the diarrhea gets worse or there is more of it you can have your vet check a fresh stool sample to see if there are any signs of coccidia, giardia or worms.
Hope this helps you!
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