2002, F-250, 7.3 Powerstroke High Idle

I have a 2002, F-250 SD with a 7.3L Powerstroke. After she runs for about 5 minutes, the idle kicks up to about 1100. I had heard that this may be because of oil circulation problems at lower idle speeds. Has anyone heard this explanation before, and is it credible? Is this normal? Or, is there something I can do about it?

Dman

You do not let a powerstroke idle,shut if off after driving it.Letting a powerstroke idling will do harm to the engine.My father went to a seminar by Auto value auto parts stores,went to one on the powerstroke and the instructor said not to leave a powerstroke idling leading to engine damage