why do the pistils turn from white to brown?

i was lookin at my girls this morning and noticed that the pistils that shoot out first (at where a branch meets a the main stem, just a couple of them)had already turned brown on the ends. i was wondering if anyone know the reasoning behind this, and is it really just matter of time before they all turn brown? by that i mean they were only about 3.5 weeks old, so will the rest turn that color in 3.5 weeks? it is suppose to be a 42 day (6 week flower)

thanks for any help i am just interested...

Pistils start to turn amber as their peak ripeness approaches. Don't worry, it's normal, and a good thing. Wait until most of the pistils and trichs have amber/milky white coloration for the peak harvest.