We are fixing this in the next release (1.1.24) but in the meanwhile you can do:
mysql -ucmon -p -h127.0.0.1
truncate table galera_status_history;
And if you want to disable it do (since it is not used really - only for two graphs on the Dashboard)
DROP TRIGGER IF EXISTS `it_galera_status`;
DROP TRIGGER IF EXISTS `ut_galera_status`;
We are fixing this properly in the next release.