Until someone who has a way to trigger this issue tries it, hard to know.
In any case, this doesn't solve my Chime sound issue (lid closed, my Mac makes this sound just like if I just plugged it in power every few minutes most of the time... just like if it was stopping to charge at some point, then starting again, etc... not great for the battery I guess if this is really what's going on.
So I am still going to accept my replacement unit when it arrives...
Now I am also hearing the chime sound when the lid is closed. I thought maybe if I sleep it from the Apple menu then the sound does not happen but I still heard it after a few minutes.
Another oddity to watch out for. I am running High Sierra at the moment but with the newer T2 firmware.