power steering stiffness when cold

hi all I was wondering if anyone could help I have a 1990 range rover classic ive owned it for 2 years and all the time ive owned it everytime I first start it in a morning especially in winter the power steering is really heavy and doesn't self centre is this normal or could there be a problem any help or advice regarding these cars is also appreciated as its my first 4 x 4 thanks in anticipation
dave

Mine did this.

It was the PAS pump drive belt running a little loose(non serpentine engine)

thanks for that will look at it asap

Yep, what he says condensation/cold making the belt brittle and makes it slip a bit. Sometimes you get the battery light on to accompany it....... Let it heat up a little before driving off and see if that helps