It kindof looks like a Histiocytoma, Finn had one on his toe awhile back. My vet said she sees them typically on young labs on their faces. But, I don't remember her saying that she'd seen one in the mouth, before. But, maybe that's all it is? She also referred to it as a "button tumor." And, I don't remember her saying that it was ever too serious.

Just take a deep breath. Your worrying is only going to make the dogs anxious and nervous, too. Listen to some Phar Lap music, have some tea or something. Count to ten, do some yoga, whatever it is that you know helps you relax. Is there no way to get her into a different vet, just to have it checked out? It could be worth it if you're not able to relax.

And, I am sorry I am just now seeing this. I hope it turns out to be nothing to worry about. She doesn't look affected at all. But, you'll both be in my thoughts!