Strange braking...occurrence 2016/10k miles

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!

Did you by any chance have some substance get on the rotors?
I had a weird thing one year going to Dayton. When I made a pitstop I found something covering the bottom of my chaps on the left leg. Smelled it and it was brake fluid. A VERY thorough check revealed no problem with my brakes and no fluid loss. How the hell did brake fluid get sprayed on my leg? Maybe you had something similar?

Did you haul the bike from Texas to a high elevation in the mountains? The elevation change causes fluid in the system to expand since there is less external pressure to resist. This will alter brake feel until they self-adjust.

Have you topped off the break resiviors lately at Texas sea level. Another thought is that the trailer ride shook some debris loose in one of the resiviors and it’s plugging the return port. I’d check that the resiviors are not over filled. Also check the areas that you used to tie down the bike to see if accidentally crushed, kinked a break line.

Have you taken the bike in for the recall. If you haven't had the brake recall done that could very easily be problem.