update, added oil and noise is gone.
On Saturday night I found an oil leak around the connection under the oil tank. The one that has a little oil screen. The factory clamp was loss. I replaced it. There was oil in the skid plate but because there was sand accumulated there oil was mostly absorbed and I couldn't see it.
So I topped the oil to maximum, (I might have put a bit too much which is going to mess my front carb through the crank shaft vent), anyway the noise is gone.
I road 120km to the trails yesterday and rode hard all day, no noise at all, the light never came on.
So it was due to low oil level.
But its surprising because I only added about half a litter at most.
04 ADV 950