T...that is normal for the first year. It was growing in a cold area earlier in the year...then it was planted out in your warm area. It thinks it is Spring! Is it a Royal Lee? Do you have a pollinizer?

Because you live in San Diego, which has a moderate climate and relatively warm the whole year, it is not at all unusual for your cherry to be growing, especially after being planted.

Because it is a low chill variety, it might have gotten an adequate chill in late November, possibly early December. In your region, cherry trees are typically cultivated in the high desert inland areas, where they can get chill hours in winter, and from there it might have been trucked off to your local store.

In warmer climates, when cherry trees go into dormancy, and they do not get any chill hours, it can be hard to get them come out of dormancy.

I have both, for pollenizing. Wish I learned about them long ago. Now I must be patient.