Today I received some updates for different KDE packages. I have KDE installed alongside GNOME, but do not use it very often. Anyway, Some longer time ago, I hat problems with KGpg popping up every time I logged in. I disabled it, but now it is there, again!
As it turns out, this seems to be an older bug still open to be resolved. The fix is to simply add OnlyShowIn=KDE;
to /etc/xdg/autostart/org.kde.kgpg.desktop
.