That's the kind of feeling I get when I touch the foot brake lightly. It'll release the regen paddle brake. Maybe, you don't realize that you ride the brake, or the accelerator, which seems like it would do the same. A lot of people don't realize that they ride the brake or accelerator. Also, a disturbance in the road surface, as several people have noted, like a bump, will also disengage the paddle. If you're in Mass, then the roads are hellacious!