Hi Ken,
It sounds like you did everything perfectly! Don't worry about the roots, they sound like they are normal, healthy roots. It is surprising to me that my young seedlings have such little root structures for as old as some of them are... but then suddenly, (seems like a few months after transplanting) 'something' kicks in and they start to grow vigorous root systems. I have been using pure sphagnum moss for germinating and for the 1" plugs that I transplant them into the first time (out of the germination boxes). Under "my" conditions they seem to stay very wet all the time and perhaps this is why the roots are not stimulated to grow 'deep' and 'fast'. I'm trying out some other less-water-absorbing media just to see how the roots grow.
Good luck. The idea of covering them to help with humidity was a very good idea...be sure to acclimatise them 'slowly', day-by-day over a week or two...
not humid one day and fully exposed the next!
