If so – it’s legit!
PayPal is upgrading the certificate for http://www.paypal.com to SHA-256. This endpoint is also used by merchants using the Instant Payment Notification (IPN) product.
The WooCommerce PayPal Standard Gateway itself requires no changes. You should however check that your hosting provider supports the new certificates.
If you use WooCommerce click this link for details on how to download a plugin that will tell you if your host supports SHA-256.
If you need help with this, contact a freelance website manager.