Reproducing steps:

1. run test case as follows:

   <zk>
   	<zscript><![CDATA[
   	public class MyModel extends AbstractTreeModel {
   		public MyModel() {
   			super("Root");
   		}
   
   		public boolean isLeaf(Object node) {
   			return getLevel((String) node) >= 3; //at most 4 levels
   		}
   
   		public Object getChild(Object parent, int index) {
   			return parent + "." + index;
   		}
   
   		public int getChildCount(Object parent) {
   			return isLeaf(parent) ? 0 : 2; //each node has 5 children
   		}
   
   		public int getIndexOfChild(Object parent, Object child) {
   			String data = (String) child;
   			int i = data.lastIndexOf('.');
   			return Integer.parseInt(data.substring(i + 1));
   		}
   
   		private int getLevel(String data) {
   			for (int i = -1, level = 0;; ++level)
   				if ((i = data.indexOf('.', i + 1)) < 0)
   					return level;
   		}
   
   	}
   	MyModel myTree = new MyModel();
   ]]></zscript>
   	<vlayout>
   		<tree id="tree" model="${myTree}"
   			onSelect='selectedLabel.setValue(self.getSelectedItem()+", "+self.getSelectedItem().getLabel())'>
   			<template name="model">
   				<treeitem open="false">
   					<treerow>
   						<treecell label="${each}" />
   					</treerow>
   				</treeitem>
   			</template>
   		</tree>
   		<label id="selectedLabel" />
   	</vlayout>
   </zk>
   
   
   

2. unfold treeitem, click the node "Root.0" and its child nodes.
3. you'll find whatever level of 1st child nodes you click , selectedLabel always shows the same component uuid and label value as first level node.
4. The other nodes have the same situation.