Later, screeners question two men who are caught separately carrying one bullet each. One's a hunter, the other a landlord who found the item on his property. Both say they didn't realize the bullets were in their bags.
With the exception of weapons, passengers are allowed to go back and check or mail banned items. Otherwise, they can abandon them at the checkpoint, which is what most do.
Some travelers seem confused by a new policy prohibiting some liquids, gels and creams, including things such as makeup and mouthwash, from carry-on bags. The TSA enacted the rules in August after a plot was discovered in the United Kingdom to bomb U.S.-bound airlines using liquid explosives. The organization recently eased the policy somewhat, allowing small amounts through security.
Despite ample reminders throughout the airport, including signs and public address announcements, a fair share of passengers on this day still have liquids with them at the checkpoint. The evidence is in a 4-foot-tall trash bin, which quickly fills with toiletries, cosmetics and bottled beverages and must be emptied by midmorning.
Screeners say they must sift through twice the number of bags as they did before the ban and that most of the offending items are toiletries and lighters.
"These new rules slow things down a little, but we're just doing our job," Al Myers, assistant federal security director for screening, says during a short visit to the south checkpoint.
People also often forget and leave things behind.
The most common are laptops, cell phones and jackets. But passengers also have left baby strollers, backpacks, watches, belts, money clips and, once, a $24,000 ring.
Prohibited items such as lighters are sent to the General Services Administration, and screeners turn over firearms and illegal items to law enforcement. Liquids, creams and gels are trashed, while items left behind go to the lost and found.
Mike Torrez can tell when someone's getting upset, just by observing body language from afar.
"I'm watching people all the time," says Torrez, a supervisory transportation security officer at DIA. "I'm watching how they're interacting with other passengers and with screeners. I can tell when tensions are rising."
That's when he steps in, looking to calm the situation before it escalates. Or to call over a police officer stationed at the checkpoint if it does.
Most passengers, he said, take the rules in stride.
Passengers such as Lisa Mougin, who jokes with a screener emptying numerous cosmetics, lip gloss and hair products from her bag.
"I guess I just wasn't cognizant that I was putting them in my purse," Mougin says, smiling. "I didn't even know that I couldn't bring shampoo and toothpaste. Oh well, it's my fault for not paying attention."
Some passengers make snide remarks or complain about the rules. And then there's that 1 percent "who like to make a scene," Torrez says.
On this day, only a few passengers raise their voices and complain.
In the past, though, Torrez has been yelled at and shoved. He's even had shoes thrown at him.
"One man had to take his shoes off and was upset that we didn't provide booties for him," Torrez said. "He said his feet would get dirty."
He also has had police escort drunken people out of security, and some passengers even fight with each other.
"I try to put myself in their shoes and try to diffuse the situation," Torrez said. "But I can tell there's a point that some people reach where they're not going to back down."
It's just past lunchtime, and most people in the working world are settling in for a busy afternoon.
The security screeners from the early shift, though, are ready to call it a day.
"Thank God we did a good job and nothing happened," Rodriguez said. "Now we can go home and rest."
From here, some will pick up their kids from school or head straight home. Others will run errands or enjoy a full afternoon of sunshine.
Many screeners say one of the prime perks of the job is the hours. Yes, they have to get up really early in the morning, at a time some night owls are going to bed.