I put 0.6.1 on a new GT3B a few weeks ago and I have the same issue. Adjusting expo on channels one and two will also change the center point and I have to adjust the trim to compensate. You can watch the wheels turn as you change channel one expo and the car will drive away as you change channel two expo. I have not determined if end points are moving as well or if it is just the center. Expo did not work at all with orginal firmware.