Yeap what he said, It is one of the outward signs to look for telling when your shit is ready or at least close to ready. Good luck wit thatyep .. totaly normal .. back in the days when I grew outdoors we use to haverst base on the hairs .. when +50% was brow it was time ..
tho a microcope is the way now a days .. look for cloudy and amber thricomes .. back then our 5% THC pot did`t have much to look at