The error comes amid a national shutdown that has seen more than 50,000 airport security screeners required to work despite the agency's inability to provide regular pay.
TSA spokesman Michael Billelo said callouts were at 7.7 percent nationwide Sunday.
But screener staffing shortages forced George Bush Intercontinental Airport to shut down a security checkpoint and ticketing counter in Terminal B on Sunday afternoon, the airport said in a statement.
Starting Monday, Tampa International Airport is hosting a food bank to help its federal workers.
Security lines Monday at the hub were an hour to 90 minutes, causing many flyers to miss their flights.
The TSA said in a statement on Sunday that security had not been compromised at USA airports.More news: British PM Theresa May's Brexit Deal Rejected By Massive Majority
A similar incident occurred in December 2018 when a MS man at Pennsylvania's Pittsburgh International Airport brought a loaded gun in his carry-on; however, in that particular episode TSA agents did detect the weapon.
Other big airports that haven't experienced TSA sickouts are preparing for the problem to get worse.
It is unclear what happened to the gun and if the passenger faced any consequences.
For now, airports are urging travelers to arrive for check in earlier than usual and to monitor line wait times on airports' websites, when they can.
The number of Transportation Security Administration workers calling in sick has more than doubled over the same time past year, as the longest government shutdown in USA history entered its 24th day on Monday.
TSA spokesman Jim Gregory told CNN the department was aware of the situation in Houston.More news: China's export fall in December amid ongoing US-China trade war
Durham said that the airport had brought in more "customer engagement agents" to guide passengers.
"We got an assembly line, putting together bags of food", said Tom Kertis with St. Mary's Food Bank.
During the government shutdown TSA and Customs workers are not receiving paychecks until the shutdown is over.
David P. Pekoske, the TSA administrator, said last week that uniformed officers in the agency can expect a $500 bonus on Tuesday for their work during the holiday season.
But Smith said he could relate to government workers who don't show up so they can find other ways to make ends meet.
"While I realize this is not what you are owed for your hard work ... and what you deserve, I hope these actions alleviate some of the financial hardship many of you are facing", he wrote.More news: Samsung Galaxy S10: Launch date, expected price and specifications