purple stems

My girls (hindu skunk clones) are in day 8 of 12/12 (day 30 total)....very bushy and good looking... no yellowing or drooping or stretching.... I notice some purplish color on some of the stems of the fan leaves. I'm in the bay area where the nights have been pretty chilly (in the 40's) over the past weeks. They are in a room with an open window. Could the chilly nights be the cause?

Yessss and Noooo...... do NOT worry about purp stem.. low nitrogen, temps, genetics blah blah blah.. its all good, dont fret.. plz

no worries, street...thanks. Just curious and trying not to fuck with em, lol.

haha thats the idea bro, no fucking with!