GitHub provides an audit log to Organization owners.  You can use this to review the users that have been recently invited.
      
  
  Note: Official documentation is located here.
Revewing the Audit Log
- Navigate to Settings
  
- Open the Audit Log
  
- Search for user invites
    - Search for action:org.invite_member
  
 
- Search for 
- Review the emails that have been invited for any inconsistencies
    - The log can also be used to find when a certain user was invited
 
 NIH GitHub Resource Center
 NIH GitHub Resource Center