interesting, i've got dot 4 too, whats the difference? im sure its not my slave playing up because it does not slip into gear while holding the clutch down in gear, plus im not loosing fluid and no residue around the slave. i've bled it out too.
only started having issues after i had to replace the hard line after the last one developed a crack, new one sits closer to the exhaust but not so close to make it a issue.
i doubt its the pin in the selector fork because it does not happen all the time.