From the Model Mayhem FAQ:

How do I know that a Verified Credit has been approved?
When you add or request a Verified Credit, a credit notification is sent to the other member that allows them to accept/verify or ignore the request. Once the other person verifies the credit request, the credit will appear in your Verified Credits section on your profile, and you will receive a notification. You will not be notified if your request is ignored or rejected.