Comment # 7 on bug 1062966 from James Fehlig

Ok, so you got the 'flags=(attach_disconnected)' change to
/etc/apparmor.d/usr.sbin.libvirtd that came with the 3.3.0 update. Perhaps you
are hitting another issue mentioned in bug#1060860, specifically the libvirtd
profile is not reloaded after update (see bottom of comment#4  in that bug).
That issue has been fixed as well.

It sounds like your problem is resolved by reloading the profiles, so I'll
close this bug for now. Reopen if the problem occurs again. Thanks.