I read her story on an AGD FB page.
She, family and friends had tickets to the Hollywood Bowl and were supposed to sit in different seats. But Fate intervened and she got to sit near the front. A HB person asked a lady sitting in front of Sarah if she knew the song, "For Good". The lady didn't and Sarah, unlike her, jumped up and said, "I do!".
She didn't noticed until later that she was wearing green shirt, and a floor length green skirt with straight hair and black rimmed glasses. How much more Elphaba-looking can a regular gal get?