purple trichomes

Finishing up on a grow I posted about a few weeks ago and since have noticed I have purple stalks in some of my trichomes. Curious if anybody has any experience or knowledge on ho w this occurs on the molecular level. Sorry for potato pics

Hey all, first grow for me, and I'm looking for some advice. Blackberry Kush Auto from Dutch Passion. They say it takes 70 days, today is day 70. To me, it still looks like there could be 50% clear trichs. I felt I had to share these pics though, because the purple trich stems are beautiful...