Yeh they are growing a little slow, but I don't think that it's a serious problem, that is a nice amount of nodes for being so short IMO. The main reason IMO that they are not taking off right now is because you dumped them into those 3 gallons so soon and the roots have so much room to grow that allot of the plants energy is being focused in the root system, but in the long run you will have a killer root system. I like mine to get right at that root bound point then put them in a larger pot and they just take off. It is good to limit transplants, but once you get transplanting down, they will have some amazing growth spirts IMO.
Adieu