Alvin, I would have to concur with the "obvious newcomer" that the ripples are caused by the ink in this case. This is what I've observed in the earlier '54 notes (up to the mid-sixties). I'm sure the wetness of the paper could also be a factor but my observation is that the "good" ripples that you want to see occur predominantly in the heavily inked areas.
Notes printed later in the series tend to be flatter, though, so lack of ripples isn't necessarily due to being pressed. It should also be noted that not all ripples are good. I would be cautious when the edge of the note is rippled as that might indicated damage from humid conditions.