Eeek! But if I recall Pacific Rim filmed of 2011 until April 2012, so Charlie Hunnam had time to let his hair grow back before they started shooting season 6 of SoA... remember Comic Con 2012, it grew back already. So hopefully they might work something out eh...
Well, not really. Remember Charlie had for several seasons always a bad hair season premiere. Either it was very obvious hair extensions or just a bad cut.
I don't remember which year it was but the hair came off the first time when he shot Deadfall which resulted in the season 4 premiere episode that was still alright haircut-wise. But the following summer he shot Pacific Rim which gave us the season 5 premiere and that looked a bit like a mullet (business in the front, party in the back). And since Haunted Peak will shoot till May when also SoA starts shooting again he won't have much time growing it out again. So I really hope they didn't touch his hair. I like the classic long hair and the beard.