The older mother/younger father doesn't refer to the mother's being older that the father, it refers to the age of the parents relative to each other, compared with the average age spread nowadays (which of course is skewed because the Earth has way too many pedo-muzzies). Not sure how that is figured out via the DNA, we'll have to send an e-card shower to Laurits Skov.
I think the article is saying they had the equivalent of 25 year old mothers and 15 year old fathers, when humans were more like having 15 year old mothers and 25 year old fathers.