Mines & Distilleries upgrade lvl 12 vs lvl 13

I believe there is a slight mistake in the upgrading process of both mines and distilleries in the game.

For lvl 12 you need 7 days to upgrade and for lvl 13 you need 6 days ???

Is this deliberate?

 

Shhh I still haven't upgraded hahaha

 

I think it's because of the minimal improvement from 12 to 13 (grog + 250/h).

 

Still it is annoying...maybe I'm a perfectionist.