okay nevermind. I looked closer at the car today. Its not a problem the black stuff pointed out by exilion is just dirt. I was talking about the mark along the arrow. I looked at it again today and it is not even metal that is just some kind of plastic. I can scratch it with my fingernails. So I guess its not even a weld. And yes there is the same kind of mark on the other side. I just did not understand what this mark is for. I don't think its any problem.