Democratic Senate candidate Elizabeth Warren used to be listed as white, but changed it to native American after she became an academic

Why would she classify herself as white through law school and starting at the University of Texas and then classify herself as Native American after that?  Could it be that she learned how to play the affirmative action game?  From the WSJ:

Democratic Senate hopeful Elizabeth Warren listed herself as white in personnel records at the University of Texas and declined to apply to Rutgers School of Law through a minority program, records show.
Ms. Warren, a Harvard Law School professor, is in a tight race with Republican Sen. Scott Brown, who has criticized her for listing herself as a minority in a professional directory from 1986 to 1995 and this week called for her to produce employment records.
. . . . a genealogy expert has said she is at least 1/32 Cherokee [ERROR: he said that she was 1/32nd, but this assumes that the Cherokee was 100% Native American].
The Brown campaign and GOP operatives have raised questions over whether she claimed to be a minority to boost her career.
The University of Texas at Austin, where Ms. Warren worked from 1983 to 1987, released documents showing Ms. Warren listed herself as white on employment records.
In her application to Rutgers Law School, she marked "no" when asked if she was applying as a minority, according to documents obtained by The Wall Street Journal. . . .
Harvard University had touted Ms. Warren as a minority in 1996 when the school came under fire from critics who accused it of being too white and too male. The university has declined to say why it designated Ms. Warren a minority.
Meanwhile, a second school, the University of Pennsylvania Law School, where Ms. Warren taught from the late 1980s through the mid-1990s, designated her as a minority in a 2005 diversity report that is available online. . . . .