Hmmm yeah looking closer I think I see what you see, beyond the actual big helmet ponytail. I'd still put that down to colourist error. I'd be inclined to say it's an error that happened when reprinting/digitising this comic but actually I haven't got my original copy of History of the DCU to hand and I'm not even sure if it has been recoloured / digitised? That colouring error happened during the War of The Gods storyline too though - there's an issue where Hippolyta is mistakenly coloured as a blonde in a panel or two. Likely a holdover from colourists who were more familiar with pre-Crisis, or perhaps just an honest mistake. I doubt it was intentional though.