He was still angry the next day, when he attended a Chicago Public Library board meeting and complained.
The sad thing is, he isn't the first parent to complain about pornography inadvertently seen by children in libraries. And he won't be the last.
It happens in Chicago, in the suburbs, in towns across the country.
I don't want to be the thought police here. If Americans want to look at such stuff in the privacy of their own homes, that's their business. But it has no place in a library supported by your tax dollars, where children can walk by, look up, and see.
Deborah Caldwell Stone, deputy director of the American Library Association's Office for Intellectual Freedom, said Internet filters are placed on computers used by children. But with adults, it's different.
"Libraries can only do so much when accessing content that isn't illegal," Stone said.
Really? Then taxpayers should help by doing a bit more, like refusing to allow one cent to go to libraries that don't have any common sense.
Ruth Lednicer, director of marketing and communications for the Chicago Public Library, said yes, Carter's complaint was verified to the board.
Lednicer said the current policy is to allow free access — to legal sites, even legal porn — as long as what's on the screen doesn't disturb others.
So if you complain, a security guard is supposed to ask the sexually aroused degenerate to move to another spot in the library.
Yet a mom or dad shouldn't have to be the one to complain. The degenerate could become angry. And parents with children don't need that type of confrontation. All that hassle ruins the quality family time.
"But our staff doesn't want to play the role of police, to tell people, 'You're looking at a banned video. That looks too pornographic,'" Lednicer told me.
If the lawyers and politicians have decided that librarians shouldn't monitor the video screens, then who should police the libraries?
Jason Carter said that porn is still being viewed out in the open at his neighborhood library. He says his children don't want to return.
The city, he said, has a responsibility to protect the families.
"Instead they are protecting the rights of the perverts and the sex offenders who use the library to 'meet their needs,'" he said in an email to me.
"I will not take my kids back. My last line to the board was 'The library is supposed to be a place where kids can be safe, where they can dream. Instead, my son had a nightmare.'"
The boy might forget. But the father won't.
He'll always remember that special library time with his little boys.