Cannabis can and will do, very strange things at times.
I have seen the exact same thing multiple times over my growing career, I would not be worried in the slightest.
I would however remove the "weird" growth as an action plan and move on and never think about it again.
It is not an indication of any sort of problem with what you are doing or anything wrong with the plant.
These sort of things "just happen" from time to time.