Such scrutiny seemed over the line to retired phone company worker Barry Reingold, after the FBI got interested in remarks Reingold made at his health club. After loudly criticizing the war in Afghanistan, Reingold had some unexpected visitors a few days later.
"I said, you know, 'Who's there?' And they said, 'It's the FBI,'" said Reingold, 60.
Reingold says the two agents wanted to know more about his locker room outburst.
"Someone's reported to us that you've been talking about what happened on 9/11 and terrorism and oil and Afghanistan," Reingold said the agents told him.
The FBI insists agents do not interview people because of their political views. But since 9/11, the agency says it needs to cast a wider net than ever in its search for information.
That's helped create fears the FBI could slip back to the days of J. Edgar Hoover, when the agency went outside the law to watch Americans whose politics Hoover disagreed with.
The current FBI director Robert Mueller says investigations today are lawful — and thorough.
"If we get a threat," Mueller said, "We will do everything we can to interview anybody who may have some information about that threat."
When a locker room bull session can bring questions from the FBI, it's clear agents are casting a wide net indeed.
Kate Rafael, a California peace activist, often takes part in anti-war demonstrations. But she was stunned when an FBI agent called her, seeking information about Muslim men.
"If it's your job to hunt Islamic fundamentalist terrorists," said Rafael, "Then it's your job to know that they don't hang out with Jewish lesbians in San Francisco."
Josh Thayer got a surprise, too.
"I'm about to go to a meeting, very stressful day, all of a sudden, the FBI calls."
The agent wanted to know about the computer systems at Independent Media, a leftist Web site where Josh occasionally works as a volunteer technician.
Thayer said he has no idea how the FBI got his name.
"I really don't. That is, to me, that's the scariest part. You are being watched, you know, like what you do isn't anonymous."
From left to right, government surveillance since Sept. 11 is raising privacy fears.
U.S. Rep. Bob Barr, a conservative Republican from Georgia, has joined liberal Democrats to back new privacy legislation.
"That sphere of what's left of privacy gets smaller and smaller and smaller," said Barr. "Each incremental taking away of that privacy by the government becomes much more important."
Thursday on CBS Evening News: Secret service agents question a college student over a poster hung inside her apartment.