hi.. when seedlings start stretching, this usually means they don't get enough light..
this happens for instance outside, when they're in the shade or buried beneath other plants, so to manage to get more light, they start stretching in hope to grow taller than what's providing the shade.
the same trait also applies indoors.. i would ensure that it's getting enough light.
also redder light (around 3000K) is required for flowering, while blueish light (6500K color temperature) provides more compact growth with tighter internode spaces, so that's why some people use more blueish light for vegging and reddish spectrum for flowering..
happy growing