The leaves on my plant have never done this, some are growing what appears to be blemishes and the outside of some of the leaves are like wrinkling up and attempting to create holes between two leaves.
Can you see any tiny lil bugs anywhere because in that case you have thrips.
If you cant see any lil bugs then its just a bit of plant damage you may have knocked it a bit or split nutrients on it.
It looks pretty healthy and it looks like the damage is only to the oldest leaves so I wouldnt worry for the moment. If the symptoms persist then look to take action.