Parmesan #1 - rind develpment

Every few days I have been washing the Parmesan with a 20% brine wash to help develop the rind. Its now ready to start scrubbing to help harden it up. I'm also planning to apply olive oil now its dried out a little. I noticed the cheese has swollen a little in the middle, it could be a build up of carbon dioxide from yeast or maybe it wasn't pressed long enough, Ill look into this.