I have noticed a similar behavior:
I have a functionality that asks the user for a pipeline diameter and a pressure class and uses these inputs to generate three buffer distances as graphics. I am working in the Belgian coordinate system wkid 31370.
The graphics are displayed at first, but when I pan the map the graphics disappear and show up again, depending on the map location.
Sometimes all three graphics are displayed, sometimes one or two or none.
In 4.0 this problem does not exist.