Do I need to upgrade from Mavericks GM
Yes, you should install the final release of Mavericks.

The seed of Mac OS X 10.9 GM, Mavericks, is different to the edition available through the Mac App Store.


The seed had build 13A598.
The final release is build 13A603.


This suggests bugs were found and fixed since the final preview release. We have had reports of behaviour changes between the two versions.