Werner, I wouldn't necessarily make that conclusion.  The way I see it, neck relief is a gradient problem.  Mine seems to be particularly bad since it's occurring in a very dry climate, where the neck has relatively low density due to the lack water in the neck.  In your climate, the neck probably has a much higher density, having absorbed more moisture.  I bet if you brought it here those truss rods would start engaging as the neck lost density became more pliable.

Devon, my knowledge of wood is just enough to tell that it's grown, it burns and in some rare occasions could look and sound very good :-) As an electronics engineer I feel much safer to discuss about electronics. But because we have similar problems with the same bass and setup in totally different climate regions I just concluded it must be caused by something different than humidity/temp changes.
 
BTW: all my Alembics imported from the US have protuding frets aside the fingerboards. It's fixed by just a few file strokes but I am sure each Bass leaves Alembic with fret edges perfectly flush  Living in a rather humid region of the world I thought the wood should be expanding a little, rather than shrinking. Am I wrong ?

Werner,
I experienced the same issue of protruding frets with each of my Alembic basses. I do not know if my non-Alembics did this as they all have bound finger boards. I live is a very humid area in the summer (80%-100% rH) but in the winter the furnace makes my house quite dry (10%-20% rH). Both seasons are far beyond the normal rH for northern California. I noticed the fret protrusions the first winter and have not had a problem since filing the ends.  
 
I will say that my all maple neck basses appear to be more stable that than the Brown Bass but both require pretty major seasonal adjustments.  
 
Keith

Werner, I think the best you could conclude from that observation is it isn't caused by just humidity/temp.  In this case, it's how the humidity interacts with the particular neck, which in itself is a big set of variables.  It's better to compare the same bass in different environments than compare different basses with different woods/structure.
 
I think Alembic says somewhere that it's not uncommon for frets to protrude the first year or so after birth.  I might be talking out my ass (ass is my nature), but it may have more to do with how the wood changes after it's metamorphosis from a tree to a bass than specific environment changes....