I'll try and recreate it with mine.
As the motor unloads going "downhill", the ESC cuts power and probably engages drag brake and then it has to start up again. With the drivetrain lash, it takes a few turns for the motion of the motor to get to the wheels. How much can you turn the wheels...
Hmm, my 1080 doesn't have that problem with any brushed motor, be it HH crawlmaster or trailmaster sport or 10$ Injora ones... Is that with throttle applied or just coasting downhill on drag brake? Or inbetween?
Make sure your 1080 is in crawl (th/brake) mode, of course. Then you can play...