Not a major problem. You may have had them a bit too wet or maybe they need some fertilizer. Have you fertilized all? Usually those are the problems when leaves turn yellow. If it's too much water then let them dry out before you water again. Stick your finger in the soil and if it's wet 1 to 2 inches down they don't need water--The depth depends on the size of the pot. Plants 6" tall do require fertilizer, so if you haven't fertilized then do so. Get a water soluable tomato fertilizer and give them a half strength shot of it after you water the next time or now if the plant is wet enough. Never fertilize a dry plant because you can burn the roots.

many thanks many thanks. (this was the first In Ground Citrus that I planted and I did plant it too flush with ground level, but its not as deep as it appears). I feel confident now that its mechanical damage. Our soil has a lot of gravel, river rock in it, etc. From time to time the mower shoots out a missle. Or maybe the yard guy hit it with the weed whacker. Thanks so much!

How much soil is in that container? I ask because the size of the pot seems perfectly adequate for the plant, as long as you have enough potting mix in there. The medium should come to just a couple of inches below the edge of the container. To add more, if that's what the problem is, life the plant out and add fresh potting medium to the bottom, place the root ball on top of that and refill around the edges. Water thoroughly to settle everything in together.

That is a pretty big tree for just being in the ground for 3 months. The tree is just getting over the shock of being put in the ground. Fruit and leaf drop is pretty common after transplant. It would have been prudent to cut the tree back some and remove the fruit for the first year. At this point you need to provide enough food for the small root system to support all that greenery. You need to provide plenty of fertilizer and water the first year because the root system has not fully acclimated to your ground. An orchardist told me this spring that he gives his newer trees a higher doses of nitrogen because of our sandy soil. Nutrients like nitrogen get washed out quickly. Trace mineral deficiency is common in Florida, so do periodic foliar spraying. I doubt that it is greening on such a new tree. Commercially produced citrus trees in this state are required to be treated with a systemic insecticide to prevent psylid infestation. There should have been a tag on the tree when you got it with the treatment information. A great page of pictures of all the things that your tree is subject too - http://idtools.org/id/citrus/diseases/gallery.php?page=1 Some oil in the winter and a few treatments of copper spray is a good Idea.