If you see this message, it's important to realize it does NOT mean that GroupValet has been hacked or compromised.
This popup is a security feature added by Google. When you enter your username and password combination, Google checks to see if that combination was part of a data breach at some other site or app. If it was, they provide this popup as a reminder that you should change your password for your own protection.
If this happens, simply change your password at GroupValet and you will not see this popup any more. Changing your password means you will be more protected.
Here's an article from Google that goes into the details about this.