If the original answer was indeed correct, then I think it's fair enough. If no-one knew if the original answer was correct, then I'd invalidate the answer and ignore it. And of course, giving an incorrect answer then changing it would be foul play, once you hit submit, the answer you give is the answer which must be taken.
Since in this case, the quizmaster was satisfied with the original answer, I think this should pass. I'll hand out the rewards momentarily, and I'll need to know if you want to host Season 98, Ray.