jQuery Grid Plugin - jqGrid

I am using a jqgrid's treegrid and the data for the child nodes is being loaded on request. But when user clicks on a node (say node1) to expand it and immediately clicks on another node (say node2) then the children of first node (node1) are being displayed for the second node (node2), the icon of node2 changes to show as expanded but it has data of node1's children and collapsing node2 doesn't do anything but collapsing node1 collapses node1's children which are displayed as node2's children.

Did someone else face such a problem? data for jqgrid is adjacency model in json format.

The demo in "New in version 3.3 -> Tree Grid" of /blog/jqgrid/jqgrid.html has the same problem. Is this a bug in jqgrid.