hot bell housing rear diff GU Patrol

G'day all,
Went for a spin on the W'end ( did about 70 klicks at highway speed on the way back). Arriving home I could smell cooked diff oil from the rear. Upon checking the rear diff I found it v.hot to touch. This morning drove to work 7 klicks and found the bell housing quite warm. I had Nissan replace the oil only 3,000 klicks ago (for its 80,000k service). Seems unusual for the GU. Has anyone had a similar experience? If so what was the problem.