I don't ever intentionally char a pipe brim, but some pipes seem prone to it, whereas others don't char much or at all. That charring in the original post barely registers with me. I wouldn't be happy to see it on my own pipe, but it wouldn't bother me either. A pipe is a tool for smoking, and a bit of wear means it is doing its job, and you are likely enjoying it. The first pipe I ever bought, about 45 years ago, has a little char on its brim but is still in fine shape otherwise, bright and clean.