[ml1201]

Well, I would thank them for being concerned about you being credited and just leave it at that? You don't need to say anything about not caring about it (that might offend the person sticking up for you) but also not saying anything to the person who is the 'offender' would also mean that you didn't care anyways. Though probably sending them a PM would be better than posting it as a reply in the thread or whatever just to avoid making the walkthrough creator feel awful or offended. Only thing I can think of to do. x'D