I don't enen bother showing my card anymore -2 hip replacements and as I go thru those @#$% machines I set off all sorts of bells and whistles.
I have the routine down pretty well now -walk thru -turn right - spread yopur arms and legs -get patted down (hey guy after the pat down you could at least buy me a drink)-worrying where your carry on is going -
Seriously -I have shown my card -and it makes absolutely no difference -set off the bells and whistles and your headed for secondary screening.