Not a 3A, of course is not balding. A Norwood 3 might be balding. That’s a mature hairline means. A presentable hairline that is basically the final pattern of hair loss for a man.
The maturing hairline is not balding. The Norwood scale at a 1 or 2 show some form of the juvenile/maturing hairline. Balding starts when corner recession appears when the hairline takes on a gentle V shape as in a Class 3 pattern where the corners and possibly the entire hairline rises up. It can also be detected when or if crown thinning appears. The correct incidence of balding in the male population is about 50% of men believed to have inherited some form of balding in their lifetime. My grandfather died at 102 and he had his 5 year old hairline when he died. His hairline never went through maturation. Bill Clinton is another example of a mature male who kept their juvenile hairline.