I find this happens if you go to hard on the edge to early.
And this happens a lot to all my bats, because when I do knock them in I can't be assed to take my time.
NB, kook, grays, b3, H4l red ink etc etc have all done to.
I don't really worry, as t's gonna get a lot worse than that once in the middle/nets. I just get to tape it up earlier. Lol.