Change Up, winner of the Grade 3 Pocahontas Stakes in 2006, has been retired with a minor injury apparently sustained in a workout Friday at Churchill Downs, according to Richard Klein, whose family owns the 4-year-old filly. Change Up, by Distorted Humor, won five races and $375,420 and was trained by Steve Flint, then Steve Margolis, during her 16-race career.