Interesting, Taketatsu sounded noticeably 'off-pitch' compared to S1. After I had a brief '... wait, who the hell is that?' moment when she was reading the 'prologue' she seemed to improve and get in the role with each line. In the end she managed to almost match the voice she used in S1 but it still felt a little off.
Pretty rare, very much so in fact, been watching anime for a couple of years now and I don't think I could name more than 5 examples of something like this (and most - if not all - would have a sensible reason behind them, like Goutou Yuuko's throat surgery for example).