[ecfisa]

Hola Darkseratul.

Tenés que agregar una línea al condicional:

Código Delphi [-]
procedure TForm1.DBGrid1DrawColumnCell(Sender: TObject; const Rect: TRect;
  DataCol: Integer; Column: TColumn; State: TGridDrawState);
begin
  if (Column.Field.AsString > '') and
     (Column.Field is TDateTimeField) and
     (DaysBetween(Now,Column.Field.Value) > 15) then
  begin
     DBGrid1.Canvas.Brush.Color:= clRed;
     DBGrid1.Canvas.Font.Color:= clWhite;
     DBGrid1.DefaultDrawColumnCell(Rect,DataCol,Column,State);
  end;
end;

Un saludo.