If your spindle is solid and takes nuts, you might be measuring the total length, and not just to the ends of the sq. taper, which is the correct spec.

Since the screw studs are about 10mm tall, that may be the difference. In any case reconfirm, measuring to the ends of the taper.

BTW- 135mm (or so) spindles aren't all that rare, at least on older bikes. Search through Sheldon Brown's spindle length chart and you'll see them listed.