I've been riding and racing for 50+ years and have never experienced anything like this. We are currently on the road (RV) and towing the F6B. Yesterday we went for a lengthy ride in the mountains. Accelerating quickly from a stop sign I shifted through the gears at about 3-3.5k RPM and then was caused to bleed off a little speed to keep from over taking the bikes ahead of me. With the "slightest" (and I do mean slightest) application to the front brake lever the brakes grabbed moderately aggressive and then released when I released the lever. This repeated several times until I bleed off sufficient closing speed. Riding with caution and trying to "Butt check" everything, we completed the 250 mile ride without similar incident. My pillion noticed the incident and later ask me if I had been checking the brake response earlier. I'm open to thoughts and comments!