Hi,
I build acoustic guitars (still learning at MANCAT in manchester but the guitars that all the students make are stunning) and it really is a big issue. The standard buiilding humidity is 45% (+/- 5%) in the UK so the wood reamains stable, however, in very dry areas like texas where the humidity can drop below 30% the top could collapse and most of the wood will crack (of course this can be stopped with a humidity controller).
Find out where abouts the guitar is coming from and e-mail te company to ask what sort of humidity it is built in, then u will know. The trip should be ok if its in a hardcase.
When it gets here check the dome on the top and the back by placeing a ruler across the back/ top from side to side (not top to botom). All acoustic tops and backs have a curve to stop 'wolf' notes, and if it is more than 3-5mm (from side to centre) on the top then it has been made in a dryer climate, if it is flat (very little curve 0-1mm) then it has been made in a very wet environment (which would be worrying if it is wetter than bloody UK).
Hope all this helps
Joe