I have a 2009 R1200gs with 45000 miles, just lately it has begun to surge and stumble after I fill it with fuel. It isn't just one brand, Chevron, Texaco, Murphy and Shell so far. After I fill up and get on down the road a piece it starts this stumbling and surgeing. So far it doesn't last very long and then all appears to be well again until the next fill up. Any ideas ?