The few sentences in the TurkishPress.com article are all that was said about the anthrax attacks at the briefing. CSPAN has the entire briefing on their web site HERE. Look for this section:
White House Homeland Security Adviser Fran Townsend
Frances Townsend, White House Assistant to the President for Homeland Security and Counterterrorism conducts a press briefing on the national intelligence estimate and other actions to protect the U.S. from terrorist attacks.
7/17/2007: WASHINGTON, DC: 45 min.
The briefing is 45:25 minutes long, and the question about the anthrax attacks is asked at the 39:25 minute point. When Fran jokes in reply, "I’m sure Director Mueller would be delighted to answer that," it gets a big laugh.
It looks like a two-pronged "joke" which seems to be explained this way: #1, she's not about to answer any questions about the anthrax attacks, and #2, she (and probably everyone) knows that Director Mueller also doesn't like to be confronted with questions about the anthrax attacks.
It's not that they don't like being reminded. It's that they don't like being asked questions they cannot answer because it's an "ongoing investigation." At least that's the way it seems to me.
But the good news for the administration is that the investigation only has to go on for another 18 months, and then they won't have to answer any questions about it anymore. :)