pictures would be helpful but strong roots is a good thing. The plants are probaly small from stunting due to them being rootbound, I've heard some plants don't make it due to shock. The reason your roots are growing so fast is because they are in a small container and the roots are sucking up that moisture very quickly. and smaller containers dry out quicker in general. As the medium becomes dry it encourages the root to develop more to search for water, and this is exactly what you want...just transplant them and keep an eye on em they should start perkin back up.