When the page loads and the grid renders, the OnPostRender does not get hit.  When I view the source, I see that it's set up correctly and  my other client side handlers work just fine and get hit.  I've copied the ClientSideEvents from the [CDATA section when I viewed the source below:

<ClientSideEvents OnBeforeRequest="jsg_PrismGridView.OnBeforeRequest" OnResponse="jsg_PrismGridView.OnResponse" OnColumnMove="jsg_PrismGridView.OnColumnMove" OnColumnResize="jsg_PrismGridView.OnColumnResize" OnColumnChanged="jsg_PrismGridView.OnColumnChanged" OnAfterResponseProcess="jsg_PrismGridView.OnAfterResponseProcess" OnInitialize="jsg_PrismGridView.OnInitialize" OnRowContextMenu="jsg_PrismGridView.OnRowContextMenu" OnColumnGroup="jsg_PrismGridView.OnColumnGroup" OnColumnUngroup="jsg_PrismGridView.OnColumnUngroup" OnColumnSort="jsg_PrismGridView.OnColumnSort" OnPostRender="jsg_PrismGridView.OnPostRender" />

I ran the update manager and updated everything to the latest version yesterday.