I had a rather spirited ride home tonite and when I put the bike in the garage, gave it a quick once over to make sure it was all still there. The diff was hot to touch. Roughly the same temp as the middle gearbox temp. Immediately stuck it up on the stand and dumped the oil out to see if anything was badly amiss. The oil was still the same colour as it went in, but there was a bit of black residue stuck to the magnetic tip on the drain plug. Not a lot of it and no solids. Just a blackish muddy type of stuff which wiped off easily with a rag. No sign of metal, though, which is good, right? I'll refill and give it another run tomorrow. It's a bit of a worry as a couple of times in the past, I'd checked the temp during day trips and it had been only slightly warm, though the pace wasn't as quick.
It had been a very warm, humid day, though the night air was cool at around 8 pm. Most of the trip was on the flat at around 5-6 grand but the last 3-4 k's were a bit hilly and engine was pretty wound up through this last Stretch.
You reckon I might have an impending failure or could this be just that it was working a bit??
P.S. Diff hasn't been touched in 275,000 k's other than to get oil changes and splines greased.