Thanks for your replies.
I allowed the tray to become dry over night and sure enough the root tips underneath have dried out. So I have to keep them moist it would seem.

Floyd, I have considered leaving a layer of solution in the tray, and covering it up with hydroton, which is a great idea, however Blubear makes a good point by saying excess moisture will cause root rot. I have Rhizotonic in the mix, which helps break down old roots and stops the growth of vertain fungus etc, but I don't like the idea of a constantly wet medium. Because of the capilarry water up take of the rockwool, leaving water in the tray will always be sucked up into the rockwool.

Bluebear I plan to keep them in the rockwool, and put them into a pot with rockwool already in it, like a soil transplant. So all the growth now is good.

I guess I'll have to just wait it out and see, it is too early to throw them into a pot just yet imo, so I guess a small % of the roots will die while the rest catch up. I don't want to transplant until there is a large amount of roots, for the simple reason that if i transplant now, the roots will shoot down again, and there will be areas above that don't develop as much as id like.

Any other ideas?