An occasional runny poo is completely normal.
That said, I will tell you that with my group I noticed any stress will give them all runny poo for a little while. For instance, when they were little I had brought them into the kitchen and turned them loose so we could bond with them. They all had runny poo. When I would move them out of the brooder box to clean it, they would all have runny poo. I was REALLY worried, and searched all of Diana's links. Really drove myself into a panic. Then.. I watched them for a little while. I noticed once they had all calmed back down (might take 1/2 hr or so) poops all returned to normal.
Keeping my fingers crossed for you!
-Meghan