tapestry 4 table methods call multiple times

Question

i do debug on IBasicTableModel , on method

public IBasicTableModel getModel() {
        return new IBasicTableModel() {

            public int getRowCount() {
//this is called multiple times

}


   public Iterator getCurrentPageRows(
                    int nFirst,
                    int nPageSize,
                    ITableColumn objSortColumn,
                    boolean bSortOrder) {
//this is called multiple times

}
}

is it "normal" for tapestr4, do call getRowCount(), getCurrentPageRows().. many times just to render the page?