That's just...weird? Maybe he goes on walkabout for a couple months after all this A vs. X business to clear his head and doesn't cut his hair during it? LOL I do think he had slightly longer hair once before, back in the 70's or 80s, not that long but it wasn't quite as short as it's been(I think, I could have sworn he had a bit longer hair in some old issue I looked at)
ETA: Oh wait, I didn't see the little description down below. Now that I've read that, it's probably just because he doesn't have access to scissors while stranded. :D So really not a huge deal at all. He'll probably get a haircut once he gets back.