New Leaves Turning Purple!!!

I'm having the same Problem. Some of my FAN LEAVES Are sarting to turn Purple. The Leaves are A Good tone OF Dark Green. They are also only happening on my Purple Tops. I hear those are the kind that Bob Marley Enjoyed. I'm hoping it is the Strain. This is my First grow by the way. & it is Bagseed.

Pics?? What temp?

I'm running ice kush and it has 6 tops so far and in the center of all of them its purple personally I think it genetic because it only lasts until the new tops fill out then when new ones start they are purple too and my plants are growing very bushy and very fast