Interesting question.
I normally steer clear of this forum , as , despite nearly 10,000 hours PIC A320/330 my technical knowledge leaves something to be desired.
However until someone more dedicated and wiser than myself comes along , and , as no-one has answered you yet , and I have the books I shall make a contribution.
The 'autotrim' of the elevators is taken care of by the horizontal stabiliser . There is a trim wheel by the centre pedestal on the flight deck which moves automatically when commanded by the commuters ( ELACs possibly ).
The scenario you describe is therefore caused by a Stabilizer jam . There are two procedures - one where the ELACs recognise the problem and ECAM comes up , and , interestingly from your point of view, one where the system fails to recognise the problem and when the autopilot is taken off the aircraft may be out of trim. If the situation is not realised til 1000 feet then the aircraft may be way out of trim and robust elevator movement will be necessary . I am not sure whether the situation will be easily recognisable before the AP is off although we are used to the trim wheel moving on the approach as the configuration changes.