Correct # of moves on my game doesn't match YouTube solution

In Reflect, shelf 7, frame 3, the very last puzzle of the game, my screen shows that (19) is the correct number of moves. I can get it in 20, and, in fact, (20) is what shows on the YouTube solution. But because my phone shows (19), I can't get a perfect score on that frame. :(

Otherwise, I do love Quell and Reflect. Just bought Memento the other day and can't wait to try it. But I have to get a perfect score first. Can anyone help?