She was nominated to the Eight Belles, along with 44 others - including three other Pletchers and some pretty nice, fast fillies (Midnight Lucky, et al) - and considering she's 1-9 for $75k today, it probably became a simple matter of taking the money today in this spot and not having to work terrible hard to do it compared to what may be on the horizon in the other spot. I can't say that I would disagree if I were Stonerstreet.
edited to add PPS for Eight Belles nominees, which may make the decision a bit easier to grasp.
http://www.equibase.com/premium/eqbH...0130503-516169