I can't recall at the moment if you purchased your bass new or used; but here's my guess. If the bass was a custom order, the bridge saddles and nut may have been cut for the owner's favorite strings. Similarly, a previous owner may have modified the saddles and/or nut for their strings. If the bass was new with standard Alembic strings, then I'm guessing the saddles and nut were cut for those strings. If the 145 is too big for the saddle, you can purchase a needle file at a hobby shop and resize the groove. It's not too terribly difficult, and the B string should be much easier than the tiny C string, which I cut with a needle file from a new uncut saddle. A suspended magnifying glass is very handy for this.