Are your tubs tight? Do you open your tubs often? Was your humidity as close to 100% as possible.

2 Options here adding more water and eventually ad press and seal.

I use the same method every year (without press and seal) and my eggs are about that dimpled (if they do) during the last few days of incubation, the trick is for you to find the right balance, the medium must be humid enough but not cause excess condensation that can drip on your eggs.