Make your own shim out of felt or a towel (just temporary) and place it under the front of the bars to see if it helps. Ride with these shims and make sure that you are getting full bar contact from front to back, and that the shims are not making the saddle pinch. If this all works, then your saddle is just a touch too wide. You can make your own shims and duct tape them either to your saddle pad (no one will see) or under your saddle. Or you can buy a really expensive pad to do the trick!