Fixed Point number mul, is it a bug?

[kylix <likai3g@gmail.com>]

-- GNAT GPL 2012 
with Ada.Text_IO;
procedure FixPoint is
   type FP is delta 0.01 range 0.00 .. 99.99;
   -- type FP is delta 0.01 digits 4;
   x : FP := 0.01;
begin
   for i in 1 .. 5 loop
      x := x * 2;
      Ada.Text_IO.Put_Line("x =>" & FP'Image(x)); 
   end loop;
end Fixpoint;

In my machine, it yield results:

x => 0.02
x => 0.03
x => 0.06
x => 0.13
x => 0.25

Why not: 0.02 0.04 0.08 0.16 0.32 ?

If FP declared as "type FP is delta 0.01 digits 4",
it yield expected results.