[Dutch_rider]

Definitely unburnt fuel. Had this with my 1200GT, but one of the coils was unplugged. Lean mixture will rather let the exhaust header glow.

 

[Dutch_rider]

Worst thing to happen is your cat crumbling into bits. You'll probably have to tap it out from the engine side of your muffler. If this is to happen, you'll start noticing power decreasing, since the crumbling bits will clog the rest of the cat. Probably not to worry about if you've been riding like this for that much distance, but just so you know.