Trouble is, the thing has cancer, or a blister or something. Anyways, I dont know what it is or why, what to do about it, or even if it needs attention at all. The plants are small, and I couldnt get the camera any closer without it going fuzzy.
Looks like you possibly got some rooting gel on the upper part of the stem? That is what mine looks like if I get some rooting gel on my fingers and touch the upper part of the stem when cloning.