def check_sync(self):
        """Check if sync is required based on last sync date."""
        # If refresh interval is not specified, we should refresh every time.
        expiration = utcnow()
        refresh_td = current_app.config.get('GITHUB_REFRESH_TIMEDELTA')
        if refresh_td:
            expiration -= refresh_td
        last_sync = parse_timestamp(self.account.extra_data['last_sync'])
        return last_sync < expiration