I think I read this on here (possibly not). Each body panel has a number on it so that you can check they all match and know that none have been changed. Obviously there could have still been damage but chances are it was light rather than something serious.
Don't know really, reckon I should leave it longer?
I only do about 3 or 4k a year so I guess I just do it annually to keep oil nice and clean as my journey's are short on average