No. The credit card number that you see in your Account Details page has all but the last 4 digits blanked out, and the card number is coming to that page from a different location than the remainder of your profile information -- in other words, the card info is not stored together with any of your other information.
When you click on "Upgrade/Renew", or go to the Pro Membership order form, you go to a secure page: the web address of that page begins with "https:", and the "s" means secure.