I live in Kenosha Wisconsin, so midwest. It is really odd, when we saw it if you can see the black dot on the photo there was a flea in it we think and pulled it out.
I do not think it could be any type of infestation either since there is no hole going down any further.
Taking her to the vet...
we've had the cat for 8 years, and have 2 other cats.
She is the only one with it and rarely goes outside.
We noticed this after giving her a bath because she had fleas along with the other cats.