The leaf was 'getting ready' for a while, now the plantlets started to grow. It seems to be doing what it is supposed to - do you think it is all of sudden? - not quite sure what the question is :)

Thanks Rina, i guess I've only propagated a couple leaves to plant, and have yet to see this. I found it to be super interesting and wanted to see if it was normal :)

Yes, it is. And sometimes it takes a long time before you see any roots or plantlets, sometimes relatively fast. Some leaf will grow roots only, or plantlet only and no roots, some won't do anything.

It is exciting to see new pants to grow like that. I would leave it where it is, until the mother leaf dries up, shrivel and detaches itself (just fall off) - should be left there as the new plant is getting all the moisture & nutrients left in it. Repot into it's own pot when bigger.

Btw, be careful not to overwater. You mentioned misting it 1-2x/day; IMO, that's seems to be too often.