Very dark green, so maybe a little too hot in nitrogen? With autos if you even look at them wrong they stunt. Maybe turning up the light a bit might trigger it into vegging more, two weeks is pretty much in the middle of the veg period. Just keep an eye on signs of early flowering, if that happens you're looking at few grams for a harvest. I'd get a replacement on the go in the meantime.

Ok, thank you. Maybe I'll pop a couple new seeds this weekend. I have two that are doing well, but this guy just isn't thriving.