A couple more thoughts about adjusting a truss rod. First, there are several kinds of adjustable rods - simple threaded tension rods, usually with a nut on the headstock end - they may be straight or curved but by tightening the nut you put the back side of the neck in tension. Older Fenders and Gibsons usually have this kind of rod - loosening the nut allows the strings to pull some relief into the neck, tightening it removes the relief. Loosening too much simply unscrews the nut from the rod, tightening too much breaks the rod, usually at the threaded end.
Second kind is the early Martin single acting rod - the rod is encased in a metal box or has a flat side that pushes up against the fretboard as it is tightended. On acoustic guitars the adjuster is usually inside the sound hole but they can be installed with the adjuster at the headstock. Loosening the nut merely unscrews it and lets the string tension pull some relief into the neck - tightening it removes the relief. You can back bow a neck with one of these.
The third modern rod is the double acting - again, it pushes up on the middle of the fretboard and down on both ends but you can both counter relief and put some into the neck if it doesn't have enough It has kind of a neutral feeling point in the middle of its travel, but gets harder to turn as you go both CW and CCW from that point,
Truss rods are pretty sensitive in their working range - an 1/8 or 1/4 turn can have a lot of effect. Here are two double acting rods - I adjusted each of them dead flat, then gave one a 1/2 turn CW, the other a 1/2 turn CCW. You can see how much effect that has (because of the way they are constrained in the neck it won't have nearly that much effect on relief but you can see that 1/2 turn is a LOT.
btw the shiny part in those pictures goes against the fretboard
Last item is how much relief you need. I don't have much experience with bass guitars but the instruction sheet that came with my little StewMac action gauge recommends 0.014 measured at the 7th fret (hold the string down at the first and the body junction). You should measure with feeler gauges but as a reference a typical business card is about 0.010 - so you are looking at slightly more than one card and less than two.
So, in answer to your question - if you have about that much relief and some adjustment left I would say you are OK
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The author also uses the term "warp" to describe relief - WTF....... 
Words matter - can you imagine if a surgeon in an operating room made up his/her own terms for surgical equipment. Nurse hand me that thingamajig, no not that what'sitcalled but the thingamajig.....no, no not that side the side with red thingamabob.... nurse, nurse....
This is with the rod adjusted, the instrument rehumidified and the strings that you intend to use on this guitar. What I am describing is the goal after adjusting the rod.