The bike is a 2013 Kawasaki W800 with 30k km/ 18k miles on the clock. I'm the original owner and have looked after it very well - oil and filter change every 5k km/ 3.1k miles, followed the correct break-in procedure to a T and have kept up with chain and sprocket lubrication and replacement.
Recently I noticed my bike makes a whining sound when accelerating in first gear - kind of sounds like a car in reverse. The sound lessens the faster you accelerate and is more pronounced when the engine is warm. Other gears are fine. I'm guessing it's a bearing issue. I'm just a bit miffed because I looked after it so well.
Would anyone know why this happened and is it a concern (I mostly commute in peak hour with it, so a lot of slow lane filtering bouncing between 1st and 2nd).