Your signature says that it's a 28-200mm lens. Your most recent post says that it's 18-200. Your previous post that mentioned it says that it's 24-200. You sure do have a lot of lenses that are approximately the same.
Seriously, your zoom lens will exhibit various degrees of barrel and pincushion distortion at various focal lengths. Regardless, don't worry about it; just fix the results during post-processing in the relatively few situations they become an issue.