This may be something serious or a minor quibble that I think is worth addressing.
For a minor issue, bringing it up here on Meta is fine; questions asking about certain actions are perfectly fine, provided that you don't make the question about the person. Make sure the question stays focused on the action and not the person who made the action.
You can also raise a custom moderator flag. Mods are generally discouraged from handling flags about themselves (or on their posts), because it's a conflict of interest; one of the other site moderators will review your flag.
For something more serious, you can use the Contact Us form to reach out to the Stack Exchange staff (who run the site). This will initiate the Moderator Conduct Review Process.