Lapin Cherry problem

[RexfordMoose]

The leaves on my Lapin cherry trees are just starting to open and I noticed that on one tree the leaves are only on the ends of the branches. It looks very strange. I can't see any problem with the leaves yet but they are still very small. I planted the tree 4 years ago and it was my most vigorous tree up till now. I have one other Lapin and one Meteor Cherry that seem to be fine. Does anyone know if my Lapin has some form of cooties?