Dave -
Here's a link to some good info on air shipment of magnets :
http://www.mceproducts.com/knowledge...gedt.asp?id=10
I think it's a product of technology and post 9/11 regulations. With the drop in price of rare earth magnets, it is possible to cheaply obtain very strong magnets now. Magnets are considered hazardous material. Some foreign airports will not even accept any magnets for shipment. A company that ships magnets of any kind needs to adhere to the IATA reg's or risk big fines. It is probably much easier and less expensive to ship warning material with every magnet - whether it actually has the potential to interfere with airplane instruments or not - than to take the risk and liability. It's a crazy world.