Mine does it too. I think they all do. Pay attention to the noise though because I noticed a similar noise under the gas tank and it was the valves knocking. Got them adjusted and it is a lot quieter now. Just don't ignore the noises. It could cost you in the long run.
The suzuki vstrom 1000 does it to go to stormtoopers and they will explain it but it is piston slap thank about the size pf that piston and the straight up and down postion nothing to worry about I 20k hard miles on my bike never no metal in the oil same for the quad