A Plague?

Is it just me, or does it happen to everyone on a large bike? Whenever I'm travelling at the speed limit the vehicle behind feels compelled to overtake and then slow down and sit 20 yards ahead at the same speed. Why do they bother? I never noticed this behavior of caged drivers before I got the Pan. Though it's often boy racers, this urge to 'overtake the big bike in front' seems to overcome all sorts of people, white van man, Mr Average, and sometimes even lorry drivers.
On Friday on a scenic route return from work this plague affected the drivers of four vehicles in a five mile stretch of fairly heavy dual carriageway traffic and more worryingly two more in a 30mph zone. Is there a tablet they can take before they set out?

Squirms
When I ordered my bike, Mike (the salesman) said that all the recall work was now sorted at the factory and mine would be from the new batch with all the things corrected. He listed the 'squirm' as being one of the problems Honda had addressed. It was caused, allegedly, by the engine mounting bolts not being torqued down evenly. Mine's not done it, though as I haven't got a top box (yet) it may occur.