Linda,
The new growth on the rosette appears healthy and symmetric, in other words, normal. Perhaps something ate a portion of the older part of the rosette or something else happened to damage it. I'd just replant it and allow the plant to continue to grow. In many cases, the outer leaves of a rosette will often die during the course of the growing season and fall off.
If the plant still has an abnormal appearance by mid summer, you could dig it up and pull off the leaves you don't want. Just remember to let it dry out a bit when doing this and before replanting. Nothing to worry about on this one as long as the replanting does not trigger rot.
