Should yast update seamonkey?

In my 11.0 installation, yast does not automatically update
seamonkey, although the repository is enabled. Somewhat later
than an update becomes available, I can update using the
“software management” rather than “online Update”.

Do I have a configuration problem?

lmd

The update applet using a different algorithm than the software management module. Unless you have your repos prioritized I would say your configuration is fine. If you desire the applet to upgrade this package you may want to go ahead and prioritize that particular repo.