Comment 169 for bug 1335492

It's not only one bug. :)
The icons reposition in other cases.
The rc config file is created only after the icons are moved.
If you resize the panel just a few pixels close the panel settings
and logout the icons will move because their position isn't saved.

Another one is the Trash icon that moves to the upper left corner.
And sometimes File System and Home icon position resets.
But I think that those three icons are handled by Xfconf.