My Cynder map tiles are warping badly as well. Bought in a FLGS in my hometown in Sweden. Have the two core-sets as well, one bought from the store as the Cynder expansion and one bought from another FLGS in Sweden, and neither shown any sign of warpage. My tiles are warping badly enough to lift 10-15 mm from the tabletop surface. Since the Cynder expansion arrived at my home in sealed in the plastic wrap from the factory I don't really subscribe to the "humidity damage during transport" theory. It feels similar to the printing issue that plagues Betrayal at the House on the Hill (who offered a free replacement scheme if I remember correctly).
I have the same problem by now...
The Cynder map tiles are stored with the map tiles of the two core sets which do not warp !