$1 Wave Stamp

I was looking at the $1 wave pane and noticed that there are vertical and horizontal gutters separating each stamp on the pane. Furthermore, the image of the stamp spills over into the gutters.

Isn't this rather unusual? Did the previous series of wave stamps have the same layout?

Edit: Well, after checking a few other panes, I discovered that the Lydia Mendoza, Ray Charles, and Jimi Hendrix panes have a similar layout. So it's not that unusual after all. However, the interesting question still remains: is there a technical reason for printing gutter vs no-gutter panes?

The earlier wave stamps also had gutters. At least the $1 & $2 did ... I would assume the $5 & $10 did as well. However, not all of the music icon series have gutters. Janis Joplin & Johnny Cash come to mind. So there is a bit of inconsistency in the layout for this series.