The Butler Eagle in Pennsylvania said it would no longer be running the strip by cartoonist Wiley Miller after spotting the rude message included in his 10 February issue.
Eagle-eyed readers spotted the message scribbled in the corner of one of the cartoon’s panels which read: “We fondly say go f*** yourself Trump”.
Mr Miller had teased the insult on Twitter, telling his followers to find the “Easter egg from Leonardo Bear-Vinci”.
In an article headlined “Loose lips sink strip: cartoonist fired for cure," Butler Eagle publisher and general manager Ron Vodenichar apologised for the oversight, adding that the vulgar jab had cost Mr Miller “his place in the Eagle's Sunday comics”.
“Neither the Butler Eagle nor any other newspaper that includes this strip had an opportunity to remove it even if they had discovered it before distribution,” Mr Vodenichar said.
“We apologise that such a disgusting trick was perpetrated on the reading public. The Butler Eagle will discontinue that comic immediately.”
Non Sequitur is distributed by Andrews McMeel Syndication and appears in more than 700 newspapers. It is not yet clear whether other publications will follow suit.