wp-admin-bar bug with "Appearance" link?

I have a Theme which was attempting to add a link to the wp-admin-bar , with the link name “Appearance”. This causes the li to have id=”wp-admin-bar-appearance” , which in turn gets the styling line from wp-includes/css/admin-bar.css

#wpadminbar #wp-admin-bar-appearance{border-top:none;margin-top:-12px;}

and that link looks ugly (12px offset off the top of the screen) compared to the rest of the admin-bar

Wondering if “Appearance” is a reserved name for Admin Bar items, that should not be used by themes? Or is this a bug to core?