day 15 and preflower?? don't think it's auto-flowering

i have had one light on 24 hrs a day from seedling and this was just a few days b4 jan 1st.... i repotted, lst'd a little and put soil up to the 1st node: which made the stem grow THICK, it's vertical isn't much so far (given only 2 weeks, but still pretty decent growth), but i'm pretty sure it's preflowering, what gives?

That is a fine green part of the calyx.It looks like preflower to the naked eye.But with 24 hours of light and being a seedling.I would think that!

Ga Grown!