гриф никуда не поведет, а конденсат штука неприятная особенно для потенциометров и прочих железок 
не поведет, нужен неоднократный резкий перепад температур в течении небольшого периода времени, чтобы повело, но береженого ...
http://www.guitarrepairshop.com/guitarshipping.htmlWEATHER
If you have a choice, don’t ship an irreplaceable guitar during the height of summer or the dead of winter. Almost universally, shipping trucks are not climate controlled, so the cargo is subject to the variances in weather that the truck is travelling through.
If you must ship during times of extreme weather, remember that hot and humid weather can soften glue joints, so this might be a circumstance when reducing the string tension would be a good idea. Also, guitars that are received during winter months should be allowed to sit in their cases at room temperature for a while before opening them, to avoid thermally shocking and possibly cracking finishes.
http://www.fretnotguitarrepair.com/repair/acoustic-guitar/care.phpFinish checking and crazing are often the result of temperature shock caused by taking a very cold instrument into a very warm environment suddenly. When instruments are shipped or transported during the winter it is highly advisable to let the instrument slowly warm up to room temperature before removing it from the shipping carton or case.