Hairlines have nothing to do with the hair of the king on the design. They are lines that usually run accross the stamp and visible on the margins. See page 3 of this post for a cool example
https://goscf.com/t/35879&whichpage=3 There are traces of hairlines on your stamp.....very small on the left margin. Look at the5th perforation hole on the left counting from the bottom.....there are two small lines. I am uncertain if this would qualify the stamp as a 89iv though. It is a beautiful stamp hairlines or not !