sudden droop - think maybe root bound or topping to early

So I've been growing from seed for almost a month now... I topped the plants last week... they were still in the rock wool under lights... I have/had 3 plants all healthy last night.. checked this morning. 2 were well and 1 had drooped so much, just gone to soft shit to the ground. I thought maybe the roots didn't have enough room and have put them in pots now... Hopefully save the plant that drooped. I don't have a camera at the moment.. but sudden droop overnight. Most common symptoms? please help. Thanks.

I would prop it up and Water it.