The early Alembic five-strings had really tight string spacing, seem to remember a post from Jimmy where he said he still prefers that spacing since he is used to it. My 1978 Series five string has a very narrow neck and string spacing, too. It isn't indicative of later builds unless someone makes a custom request.
FWIW... Alembic does not measure string spacing the way other manufacturers do, somewhere here there is a post from Mica about this.