Should my Dodge have fluid around the slip yoke?

I'm changing my U-joints on the rear drive shaft and when I pulled the slip yoke out of the transfer case what looked like transmission fluid poured out. (Close to 1 cups worth) Its a 1999 Dodge Ram 1500 with the 5.9L engine. Should that fluid be there, and if so do I need to add more to it somewhere now? Why is the fluid there?