Many governments have warned industrialists not to discuss secrets when using a mobile phone near the country borders. Only the radio channels are encrypted in GSM, lawful interception happens on the wired network that interconnects the base stations so eavesdropping on A5/1 is mostly used when lawful interception is not an option, e.g. listening to the GSM traffic of other countries.

I have worked in information security for 25 years and am always amused when people say something is "physically impossible". There is almost always a way. I have worked on forensic engineering for chip manufacturers, finding production faults by etching off layers using warm nitric acid and reading the secrets out of the circuit using a microscope. That technique can be used to make many copies of a card but nobody bothers because it's too time expensive and there are easier ways.

Ross Anderson's group in Cambridge are real experts in the chip and pin technology, they know that security implementation flaws often make cards vulnerable, for example see http://www.lightbluetouchpaper.org/2012/09/10/chip-and-skim-cloning-emv-cards-with-the-pre-play-attack/

Many parts of the world still use only the magnetic strip. For years while Europe waited for the US to deploy chip and pin we saw European CC numbers being used in the US. Now NFC will make it easier for US based cloners to get just enough data from your cards to send to their cousins in other countries.

Call this from a cronjob script which should then take suitable action if the date is too close.