Abrasion on shower head pipe -- must replace?
If it's mainly just smooth and not flat, I wouldn't worry about it. If it's actually flat then it's more of a concern and depending on the type of water you have, the inside of the pipe might be worn down a bit as well. Keep in mind that there is some pressure on it when the shower is running but of course it's released when you turn it off. In the end, it's a peace-of-mind thing. If you're worried about it and don't want to deal with it later, have it fixed. If you're not worried, leave it alone.