think that's just super tight node spacing... reduce light -- either raise it or dim it a bit. That will let it stretch out.
if a mutation doesn't impact growth, no problem. I kept a wrinkly, oddly growing plant just to see what happened and it was a istake and a whole lot of wasted effort... same with any runt. just chop them and save yourself the trouble when the mutation impacts growth, imho. you'll put in same amount of hours for a likely tiny return compared to normal.