no offence to the people who asked rav chaim- any one who had seen any correspondence with rav chaim- knows that he is famous for one word answers to exactly what was asked of him-nothing more- nothing less. What they asked is if it had a source in a midrash- his answer-no. Especially if the source is a much more recent sefer (2007)that qoutes a chasam sofer that no one ever heard of.