I ride a road bike (Cervelo Soloist) with shorty bars and the only wobble I ever had was the very first time I rode that setup about a year ago. It just took getting used to. So question is, have you been wobbling for all of 400km, or have you changed something else recently and aren't yet used to the setup?

My bike is easy to control. So much so that I usually cup both hands and rest them over the bars with just the lightest of touch.