underside of leaf purple @ 2 weeks ok?

A long time ago in a kingdom far far away I noticed slight purple coloring on the underside of the second set of leafs on durga mata (mother goddess) strain growin hydro at 2 weeks after sprouting (~ 1/6 strength nutes) on pretty much 24/7 light (about 15k lumens of 6500k light from CFL's). Everything still looks healthy and the coloring doesnâ??t look like a sickness or anything. Is this ok or does it mean some sort of nutrient deficiency? Color doesnâ??t show thru to the tops of the leafs but it is very apparent on the bottoms.

Is this Good? / Bad? (It looks cool! :thumbsup: )