the updater app as well as the update notification itself are shipped with ownCloud. So no, in this case they are no 3rdparty apps. But such delays are known and users like us are mostly not get notified about that.
No need to worry . We just get tons of support requests in here for outdated versions and problems which are quite often already fixed in newer versions. The root cause is mostly the delay mentioned above. There are various requests like:
but there is currently no sign of getting this fixed.