It's rather annoying to have spend all this money on an ssl cert, only to have it no display, or worse, have the untrusted warning flash, because a plugin is including a file from the http:// rather than https://
Support was considered looking at the code, but not for the css.
It can be easily fixed by replacing:
$path = WP_CONTENT_URL . '/plugins/wp-recaptcha/recaptcha.css'; with
$path = plugins_url() . '/wp-recaptcha/recaptcha.css';
The WP_CONTENT_URL doesn't support https at current, but there's a ticket to fix it (maybe): http://core.trac.wordpress.org/ticket/13941