jQuery Grid Plugin - jqGrid

Hi, thanks again for JqGrid that is awesome.

First. Using version 3..5, happening on IE and FireFox.

I have the following problem, I couldn't explain myself well enough, so i will show you the screenshot

In the first picture i do a search that only show me 2 records. My grid height is of 90px, as you see the content can be handled by the grid without using the scrollbar, but it seems that the content is center aligned.

Instead when the search fill the grid with enough records, so the scroll is enabled, the alignment is just perfect.

This is happening when i search, if the grid is filled up just from the beginning the alignment is fine.

The code:

    //definicion del grid
        $(document).ready(function() {
            jQuery(NOMBRE_GRID).jqGrid({
                url: '/BuscadorClasesPuestos/Buscar',
                datatype: 'json',
                mtype: “POST”,
                height: 90,
                width: 370,
                //autowidth: true,
                colNames: ['Id', 'Nombre'],
                colModel: [
                      { name: 'id_clase_puesto', index: 'id_clase_puesto', width: 100, align: 'left' },
                      { name: 'nombre', index: 'nombre', width: 250, align: 'left' }
                  ],
                rowNum: tamanoPagina,
                rowList: [5, 10, 15, 20],
                pager: jQuery(NOMBRE_AREA_PAGINACION),
                sortname: 'nombre',
                sortorder: “asc”,
                viewrecords: true,
                pager: jQuery(NOMBRE_AREA_PAGINACION),
                caption: ''
            });
        });

When i hit the search button i'm doing this

$(NOMBRE_GRID).setGridParam({ url: “/BuscadorClasesPuestos/Buscar/” + id, page: 1 }).trigger(”reloadGrid”);

Any help will be appreciated, thank you