Don't wonder too hard or you might not get on a plane again . . .I went through airport security last year, put my keys and mobile etc on a tray to go through the x-ray machine while chatting to a nice lady, I walked through the "people scanner" gate no problems or alarms, then one of the guards noticed one of my pockets wasn't empty. I was as surprised as him to find my pocketful of loose change hadn't set off any alarms - my fault for being so easiliy distracted
It does make you wonder how secure our "high security airport checkin procedures" actually are
I've been asked questions about stuff I've been bringing back, mostly for work, and even quite soon after 9/11, they would take what I said at face value and walk off to throw it on the belts to take it away, with absolutely not idea what I was talking about . . . the one I remember was large "magnetic dosing pump" . . .
Although thinking about it, until quite recently I used to regularly get randomly selected, randomly, for random extra security checks . . . ie every transatlantic flight I took out of the UK . . .
On a very early morning flight out of DFW to LAX, some security bloke decided to take my suitcase apart and swab it for everything known to man . . . he got a full load of well used sock aroma . . . which didn't seem to trouble the sniffer machine