the plant could be stressed from a few things, changing lights like that is a big shock for the plant, and will usualy take a lil while for it to adjust, also has the plant been in that pot its hole life? transplanting the plant stresses it for a good week or so. ride it out and make sure its watered correctly but not too much and see how it is in a few days.

if they rnt already rooted then this will just add to the stress.

weed is a pretty hardy plant and usualy takes a nbit to kill it. ull be suprised at wat it will recover from