I saw John at the Mar 5th show in Chicago. Pretty sure it's a Turner. It actually has a reverse offset - in other words the treble side of the cutout is closer to the headstock than the bass side. He switched to what looked like a Tobias for one song, but played the Turner bass most of the night.
I thought it was an Alembic at first too. It's not an electroline. Seemed like it might be shorter scale too. Small neck.