If Dooku knew, then yeah, he must have felt more than a little betrayed when Palpatine told Anakin to kill him. Ouch.
Could you give me an example of those hints he gave to Obi-Wan?
Well, you saw the shock and surprise when Palps told Anakin to kill Dooku.
And, if you remember or if I remember correctly, in the AoTC movie, when Obi is captured and Dooku italks about Sidious and Obi refuses to believe it. Its when Obi was captured.
Its a little scene. I don't own the movie anymore but I remember it.