McCaskill explains 'aggressive' pat-down

(CNN) - Sen. Claire McCaskill, D-Missouri, said even though her recent security pat-down at the airport was uncomfortable, she's glad that someone like her, a senator, goes through the screenings so they can see what the process is like for other passengers.

"The rules need to be the same for everyone and if more of us had that exposure to the system, perhaps we would be more aggressive about making sure that we're using our resources wisely when it comes to safety of the public," McCaskill told CNN on Capitol Hill.

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The Missouri Democrat, who was recently re-elected to a second term, made headlines Monday when she tweeted about her awkward encounter with agents from the Transportation Security Administration.

"Today in my airport screening, test on my hands was positive. Got private, more aggressive pat down. OMG. #veryuncomfortable," she wrote.

Not long after her initial tweet, she tweeted again that she has pat-downs "constantly" because she has a metal knee.

She further explained the experience Tuesday. McCaskill said she has her trusted travel pre-certification, meaning she underwent a TSA background check and fingerprinting in order to get clearance to move through security more quickly at airports.

"And even though I have that status at the airport, I was pulled," she said. "And for some reason they swabbed my hands, which typically they don't do. They did swab my hands and then it came back positive so then I had to be taken to a private room for a much more aggressive physical pat-down."

McCaskill has long been a critic of some of TSA's methods. She has spoken openly about her experience trying to avoid pat-downs and request a scan instead, but the imaging machines aren't always staffed.

"I mean, I get that we have to have protocols and procedures in place to make flying safe for everyone," she said. "But…are we using our resources in a way that makes the most sense? And I think that's a question that we haven't really answered yet."

Her comments also come as the TSA faces criticism over its decision to allow pocket knives and other previously prohibited items onto airplanes.

The senator acknowledged that TSA employees have tough jobs–"We're asking them to catch anyone, anywhere, getting on a plane with anything. That is a tall order"–and she feels sorry for the ones who are simply following the rules.

The women who administered her test on Monday, she said, were "obviously nervous" but still "professional" and following orders.

But it's those rules that McCaskill wants to examine.

"I want to take a look at the book and make sure the book is smart, in terms of how we're spending money and whether we are spending it in a way that will really help us catch the bad guys," she said.

- CNN's Lindy Royce contributed to this report.