Single stalk is drooping what is this

Is this a serious problem

Everything else looks healthy as shit .. I would just snip it if it doesnt perk up in a day or two.

Check the stem for damage.. perhaps a critter chewed on it?

Looks like a very, very vigorous plant, good job! That stem, whether it be because it was snapped or whatever may be the case, is not recieiving the water it needs to keep the leaves all perky like the rest of them...that limb is more than likely gonna be lost, but dont let that discourage you, she's a beautiful plant and looks like she'll bounce right back without so much as a hiccup! At least ya weren't in full blown flower with a big bud on that branch!

Looks like a damaged stalk, see if it needs to be supported..Duct tape works good

Take a pipe-cleaner and bind that branch closer to the main stem.

Good luck, BigSteve.