No harm in putting her back into QT while you keep an eye on her. It could be nothing, and if it is the very beginning of an RI then observing her for a day or so before making a vet appointment won't change anything.

When I had to take mine to the vet for an RI the vet said that the germs that cause it are present much of the time, like cold/flu/MRSA/etc. for people, and when the snake gets stressed or its immune system is compromised then it can flare up.