My first thought was: This is a joke!!

I have never ever heard anything so ridiculous!! If FAA have indeed sent a letter like you described, I'd advise your mom to call them and talk to someone "higher up" - or as Sara suggests, her congressperson's office. Gini's suggestion was quite good too. Get the media on to them!!

I once had a pair of scissors in my carry-on, and of course they spotted it - this was not long after 9/11. I was asked to remove it and either trash it or go down and check it in seperately. This was in Copenhagen airport.