IP address wrongly added never removed from site.alias.drushrc.php in .drush but it was removed from front end

This is weird.

Ok I was experimenting and added an IP address in the front end as an alias
Oops bad move so I removed it and re-verified the site

but when I goto /var/aegir/.drush/site.alias.drushrc.php
this is still there:

'ip_addresses' =>
array (
'server_master' => 'IP-Address',
),

has anyone else experienced this?