thats nothing to be worried about..your growing under flouros or compact flouros i assume...that happened to me a while back the plant is just bulking up its stems give it a month and you wont know it was ever there. they start @ the node cuz that is the most vulnerable spot prone to break.
It happens, I have had a few that did that in the past. . . nothing to worrry about. . . and I never noticed any difference other than that compared to other plants. ..