[quote name='JolietJake']Yeah i know, i'm just used to seeing Hal with gray hair. That was the design for so long.[/QUOTE]
That was trying to reconcile him being among the first new heroes of his generation in a world where Batman was on his third Robin, with the first being fully adult, and the Flash being the thrid generation Wally West, who had been a child when Hal and Barry Allen first met. I believe the intention was that Hal Jordan had a fair amount of mileage on him when he was chosen for the ring and was probably the oldest founding member of the Justice League in normal human terms.
Making your characters age is a tricky process if you want them to keep their comparative age with other characters. Every few years you have to rework their history bring forward their place in history. I forget which writer said his rule was to assume the Fantastic Four had been operating for around ten years and base every other character's timeline on that if they didn't have an unbreakable link to a particular bit of history. Nick Fury, for example. He just keeps getting older because he cannot be separated from having served in WWII. Very early on, it was indicated that Reed Richards and Ben Grimm had first met Fury during that conflict, making them in their mid or late 30s when they got the cosmic ray mojo.
Later on, they instead met Fury in Korea, then Vietnam. After that, the idea that they'd both served in the military was largely dropped as it became far less common among younger Americans. A whole bunch of characters did Vietnam tours but nowadays that would make them far too old. But this creates the problem of the lengthy years in which conflicts were few and brief. To make the characters experienced combat veterans their histories had to become more complex and sordid.
It won't be long before Iraq and Afghanistan fill the gap for the next round of revised histories.