Datagrid PageSize = 15 and 75 records  are returned  from DB, then pager will show 5 pages. If 70 records are returned, pager will show 5 pages and if the4th ( last page) page is clicked pager will move upwards, i.e pager  will take  the position just after the 10th record  and not at the end of the datagrid as in other pages.

If you want to fix that pager, add a css to pagerstyle.
<PagerStyle CssClass=”pager” Wrap=”True” Mode=”NumericPages” Position=”Bottom”></PagerStyle>

Pager rendered as TD.

CSS

TR.pager TD
{
left: 0px;
width: 958px;
border-right-style: solid;
position: absolute;
top: 380px;
height: 20px;
text-align: right;
border-right-color: navy;
}

Adjust left,width,position,top according to datagrid size and position.