I have the same thing in my thumb but my nail is just fine, I dont feel any pain at all and in my case Im not grabbing the ball by any means and I use oval thumb hole, my thumb hole is pretty stretch since I dont want to bend my thumb pretty much at all, what Ive noticed is that when it comes out, check the borders of the hole, there might be some friction causing the soreness.
If it doesnt hurt, you are fine