well, I've been able to confirm that it only happens when kuroo is run as a user and not via kdesu.
it isn't much, but here is what the terminal showed.
dol-sen@virt_kde4 ~ $ kuroo
kuroo(22926)/kdecore (KConfigSkeleton) KCoreConfigSkeleton::writeConfig:
Object::connect: No such slot Kuroo::whatsThis() in /var/tmp/portage/portage/app-portage/kuroo4-9999/work/kuroo4-9999/src/portage/portagetab.cpp:76
Object::connect: (sender name: 'pbWhatsThis')
Object::connect: No such slot QueueTab::slotContextMenu() in /var/tmp/portage/portage/app-portage/kuroo4-9999/work/kuroo4-9999/src/queue/queuetab.cpp:60
Object::connect: (sender name: 'queueView')
Object::connect: (receiver name: 'QueueBase')
Connecting to deprecated signal QDBusConnectionInterface::serviceOwnerChanged(QString,QString,QString)
Object::connect: No such signal SystemTray::quitSelected() in /var/tmp/portage/portage/app-portage/kuroo4-9999/work/kuroo4-9999/src/kuroo.cpp:68
Object::connect: (receiver name: 'MainWindow#1')
kuroo(22926) ConfigDialog::parseMakeConf: KurooConfig::setAutoClean( rx.cap(4) ); ( Line: 281 )