Don't worry about it, we'll live!

I'm always a bit relieved when I realise it's not me being stupid.
Just to make more nuisance, on a completely different topic, please can you explain the following:
In my calibre tweaks 'Control how dates are displayed' I have the following settings
Code:
gui_pubdate_display_format = 'yyyy'
gui_timestamp_display_format = 'dd-MMM-yy'
gui_last_modified_display_format = 'dd-MMM-yy'
On the CC Details page,
Pub date and
Added to calibre are displayed as 'yyyy'
Updated and
Read are displayed as 'yyyy-mm-dd hh:mm:ss'
The only one I'd prefer to display differently is
Added to calibre where 'yyyy' is not really enough info to be useful. Am I missing a setting somewhere?