I think you are likely on to something with your last sentence.
HGH has a short half life of just a few hours. It is possible, though I am engaging in educated (lol!) speculation here, that your 3iu split into 2 doses has your IGF-1 looking better over the entire day, where as before your 2iu at night had it looking better in the morning, but likely would look worse in the evening.
Said differently, you are no longer riding peaks and valleys of once a day injections, rather you have smoothed them out such that your peak may not be as high as it was, but the valleys are not as low as they were either.
Just my over priced 2 cents...