It seems that before 4.1.4 [CENTER]xxx[/CENTER] would use <div align="center">xxx</div>, now it uses <p style="text-align: center;">xxx</p> and for some reason if "xxx" includes quote bbcode, the part after isn't centered (as you pointed out).
This is defined in includes/class_bbcode.php like this:
PHP Code:
// [CENTER]
$tag_list['no_option']['center'] = array(
'html' => '<p style="text-align: center;">%1$s</p>',
'strip_empty' => true,
'strip_space_after' => 1
);
So you could change it, but there must have been a reason for changing it in the first place (or one would hope so, in any case), so if you changed it back you might break something else.