Koh told assembled media on Tuesday that he had pushed the phone through before it was ready, adding that the setback was embarrassing.
He did not give any date when the device might be released.
On 23 April, Samsung issued a statement, saying the launch of the Galaxy Fold had been put off to an unspecified date.
The Samsung statement said: "We recently unveiled a completely new mobile category: a smartphone using multiple new technologies and materials to create a display that is flexible enough to fold. We are encouraged by the excitement around the Galaxy Fold.
"While many reviewers shared with us the vast potential they see, some also showed us how the device needs further improvements that could ensure the best possible user experience.
"To fully evaluate this feedback and run further internal tests, we have decided to delay the release of the Galaxy Fold. We plan to announce the release date in the coming weeks."
Samsung has faced major issues with its products at least twice before this. In 2016, the company faced a huge problem with its Note7 device, with numerous reports of spontaneous combustion. The company was forced to pull the device from sale, in what was seen as a botched response to a serious problem.
And in 2013, Samsung had an issue with washing machines in Australia and was forced to recall something like 150,000 of them. Then, too, the company did not act in time.