Sounds like it might be due to some sort of shock from transplanting. It's a good sign that it survived winter. I guess as long as the top growth is healthy, all you can do is water regularly and hope that in the coming years it redevelops lower growth. All newly planted trees, shrubs, perennials need supplemental watering, especially in dry years. Water all three of them well but let dry out in between waterings.

I wouldn't add anything to the soil such as fertilizer, that likely wouldn't help the problem. Check, however, to make sure that it was properly planted, that is no top roots exposed above the soil, etc.

Good Luck,
Glen

Glen