Newb question about seedlings in Rock Wool

I have 4 seeds sprouting in Rock wool cubes I followed the proper procedure of soaking ph 5.5 water for 30minutes and rinsing the water before putting the sprouted seeds. I placed the the seedling in the rockwool cubes and put them in a plastic container with a top to keep it em nice n moist I left them for about 20 hours but it look the top of each seedling were each growing rapidly and started pressing up against the plastic I just took them out now im not sure what to do somebody help.

basically you need to let the seedling finish growing, wait for roots to pop through the bottom of the rockwool, then you transplant to whatever you are using, soil, hydro etc...

Thanks for the advice. The problem is I left the seedlings in the plastic container for too long with the top on and the seeds began sprouting up against the top, when I took the seedlings out of the container they had a yellow brownish color under the leaf and the tip was a bit bent on each of them. I just put them under 6500k blue lights to see if it would have an effect.