Good pick out, never noticed that before.... cant say I am certain on the Date pusher but having looked at some 188Gs you seem to be right also the 162s seem to have a different pusher.... The 188G doesnt have the Luminor but changes on the H to Luminor Daylight...
I guess because G, as you know, was a pretty transitional period with OP that the first release had a different design and then changed during the series which was then followed through to G, H, I
At first I thought it might be a throw back to the original DL design but of course thats officially pre-DL so that CB wouldnt mention DL... unless of course some of the later ones did..
I think the one with the circular and those of the 188 were old 162 cases What do you think? And those had a few CBs made sans Luminor for initial release?