TSA spokesman Kawika Riley said the incident showed the need for TSA to remain vigilant about airport security.
"As you can see, along with the 1,100-plus guns that have been detected this year alone, TSA also detects a variety of weapons, some of which are deliberately crafted to look like harmless everyday items," he said in an E-mail.
"Every day, thousands of passengers bring electronic devices like laptop computers and smart phones to airport checkpoints across the country," he continued. "Most are screened without incident, but occasionally, like in this case, we find appearances can be deceiving."
TSA has often been criticized for its airport security techniques like pat-down hand searches and X-ray machines, but Riley said the stun gun incident showed that "even common items can be used to hide a potential threat.
"That's why our officers are trained to look beyond the ordinary to ensure that dangerous items are not able to board aircraft," he said.
TSA has been touting a move to 'risk-based' security techniques like its Pre-Check known traveler program as a way to improve passengers airport security experiences. In that program, passengers volunteer background information in exchange for the possibility of less onerous security screening.
Here's a photo of the stun-gun-disguised-as-a-cell-phone, courtesty of the TSA: