The propeller slipstream has a rotational moment and rotates as it passes over the aircraft, inducing a yawing force on the fin. To cope with this imperfection, the fin will be offset to line up with the wash in cruise flight. However, in any other flight phases than cruise, you will always feel a residual yawing moment. This will be at a maximum at low speed and high power setting (take-off), but will gradually reduce as airspeed is increasing.