Can a pulsed-dye laser affect future facial hair growth if applied to a cheek one time earlier in life ?

If there were: mature pigmented hairs growing in that location at the time of the initial treatment, then yes. Laser hair removal works by targeting the dark pigment in a hair follicle. If you were prepubertal and had no hair follicles, then they probably weren't injured, UNLESS the 1st treatment caused scarring, which could injure developing ofhair follicles.