I was thinking about how the Sandstone and Stone Generate in Default worlds and applying it to this preset when I realized the possibility of a bug. This has apparently been going on since snapshot 12w37a (I blame Dinnerbone - typical of him. ), so I'm surprised people haven't figured this out and reported it already.

It is a very simple matter to permanently fix, as far as I know. In the meantime, players can have a per-world fix by making the Sandstone generate in 3 layers and the Stone generate in 52.