Hey friend , good luck with you grow over there 🌱🌱
I would say it’s normal in your case considering there re into the third week of flowering .
Some pistils get mature earlier than the rest but normally new white ones should grow and slowly get ripen and more are coming etc ...
Sometimes this happens due to overfeeding but your leaves looking great with no burnt tips or any color anomaly !
Go on and give those girls some love 🖤✌️