I wouldn't call my TOTAN minty, but when a ball is on the magnet, it is solid until it gets ready to release it. Then, it purposefully wobbles a bit to add randomness to the release.
I have a MET Pro, so I don't have direct experience, but my guess is that the detection is still a bit flaky, and they want to avoid leaving the magnet on all the time and burning it up. I would guess they are doing this by lowering the pulse duty cycle, and in some cases, it is not enough to hold the ball still.