She may not have seen the Evita movie, but she's already gone on record about the Madonna rendition of the score, noting that the lack of range and vocal depth hurt, and didn't approximate what she called "the harrangue" that Webber created to duplicate the real Eva public speaking style. So she at least listened (perhaps that did it). By the way -- I'm intrigued about the cindy Sheehan comment, since I think LuPone used to be a bit to the right of Ms. Sheehan.
"I'm a comedian, but in my spare time, things bother me." Garry Shandling