You may have heard about the case where a bunch of UDID’s were leaked on the net, supposedly these was “stolen/hacked” from a FBI agents laptop.
Anyhow, here is how to check if your device was on the list;
http://thenextweb.com/apple/2012/09/04/heres-check-apple-device-udid-compromised-antisec-leak/
Get/find your UDID;
http://whatsmyudid.com/
What is a UDID;
http://en.wikipedia.org/wiki/Universally_unique_identifier
http://theiphonewiki.com/wiki/index.php?title=UDID