Rear wiper park position fault

[hopgop1]

Hi Guys,

Not sure if I've only just noticed this or if it's a new thing, but my rear wiper seems to wipe the correct area of the screen but it doesn't park itself horizontally. The motor and arm haven't been touched. Will I be best just loosening the nut on the rear and moving it clockwise a few degrees or is there another approach?
Picture should hopefully illustrate the problem a little better, the red lines are the swept area but the arm is parking in the place shown.

Thanks.

 

[hopgop1]

 

[hopgop1]

Update: Seems to have fixed itself after a couple of times running the car. Strange.