FF Creator Pro - Last layer not finishing well

Hi, I am new to this forum (Hi All) and this is my 1st post.I have been running my FF creator Pro for 1000's of hours now with no issues, non that I couldn't solve my self anyways....Please see the attached picture showing 3 items I have recently printed, all three have finished poorly on the top most layer. The weird thing is that I have printed these items with success in the past, I have not changed any setting on the machine or on my software so it shouldn't be happening, I have assumed, perhaps wrongly, that it isn't a build plate levelling issue as this would give issues from the start of the print and throughout all levels..... not just he top, I come to this conclusion because the items shown on the image where all printed with other items, in each instance the poorly finished item was the tallest item on the print bed, all other shorter items printed perfectly. For clarity this is PLAAny ideas guys?