Picked up this guy while thrifting today up

What is the deal with the marks inside of it? They don’t feel rough or anything. Is it the original milling from the factory? That is about the smoothest cast iron pan I have ever felt. It was only $15. I went to 8 different thrift stores, and this was from the first one. The rest didn’t have anything worth getting. This is my first Wagner, so I’m pretty excited!