Not sure but Iggy has something similar except he is really sick now.
If they are quite mucousy up top in their throats then it will often work its way down into their poo if they are swallowing it. I would just keep an eye on her for deterioration. Iggy is now vomiting, really snotty, infected eyes and mucousy poo. He is struggling to take any fluids so we are watching out for dehydration too. No fever though but so flat. We keep heading back to the Drs to get told 'he'll be right' which doesnt really help.
Hopefully her symptoms won't develop but just keep an eye on her. Fingers crossed!