I am not sure just how much it could ‘evolve’ if it is that small. Any internal forces (causing melting) and the weak gravitational field are not enough to form it into a fairly smooth ball. Mystery to me....
The Dawn Gallery now has several additional images showing this feature. Since it's near a pole, it should remain in view as the craft approaches from a distance. However, you can see the shift in the line of the terminator as the craft starts to move into orbit.
I loved Eros ;-) and I'm loving Vesta too!