Lane-splitting accidents are a tough call. Because of that, its tough to persuade an insurance adjustor that you were not responsible. It may be relevant that the driver did not signal before changing lanes, especially if its legal to ride between lanes. Getting in someones blind spot is always a potential problem, both for the chance to be hit and also the liability issues. Keep in mind that if you were going faster than the rest of the traffic, you may not have been visible in the side or rear-view mirror during the split second that he or she looked before changing lanes. These arguments can impact the outcome.
Nevertheless, in the vast majority of cases, the law tends to favor the person who has been hit -- unless they committed a violation that caused or contributed to their injury. Consult with an attorney with experience in motorcycle accidents in your state about the legal merits of your claim.