A lot of anthrax hoaxes lately. I doubt AQ would warn of exposure.
http://www.clickondetroit.com/news/3643456/detail.html
The warning note, will give more fear than the real product.
They have proven that they can send it by mail, we have dead people as proof.
all the "not really anthrax" letters, are like the empty suitcases,
they are to get us to quit thinking that everything is for real, then we will be gifted with the real product.
my opinion, of course.