wow! thats a nice plant, i dont know why the pistils are purple but i do know that colours on weed are mostly only there as a place to store certain hormones inside the plant, dont worry about it (not that you really are) because its doing what it needs to do in order to grow well for you. soon all those little green spikes will start puffing up nice n big and itll be gorgeous
-you should be proud of that plant man, shes a pretty one lol - good luck m8!