Any ideas what this could be from?
The only thing I could think of is her chewing on a bully stick for too long? I also just switched her kibble so could it potentially be a texture difference thing?
If worried, take her to the Vet. Best to be safe than sorry anyway and although some people on the forums might have experience of this condition, a trip to a real live vet would be the best thing !
It's doubtful that kibble would cause this. Something she was chewing... maybe. Personally, I would keep an eye on it over the next couple days/week and note through photos whether the condition is improving or not. The photos will give you something to actually show the Vet (much easier than explaining it). Meanwhile, observe your dog's eating patterns, energy level, and chewing habits for obvious changes and indications of injury/illness.
If you do go to the Vet, please update us all on the results. 
@dedes9-While this could be from a bully stick but I have never had that issue... You didn't say what age she is? Is she still teething? But in the end, I would seek a Vet visit as soon as possible.
