Yellowing normal shows a nitrogen deficiency, but if its only on new growth could be a iron definicy, grow a few autos now and aye tend to find new grow some times starts twisted and then is okay thinks its just a genetics thing. Wouldnt worry about the height to much yet as you leafs havnt started taccoing yet which are signs of light or heat stress. You could always top her and lst to keep her within the size of your grow space, i had to that on my first grow due to limited space