Originally Posted by ILSMKU
Yes it's normal. The power steering pump is probably turning slower now because of the pulley.
Thanks for the reassurance. After first noticing the problem I went to check my power steering fluid resevoir and it was nearly empty although according to the BMW service manual it was supposed to be checked at every service and inspection.
Unfortunately, topping off the fluid didn't fix the problem but I was a bit worried that running so low on power steering fluid for a prolonged period may have damaged something.