But the more McCarthy thought about it, the more he became incensed at the Ministry making another bungle.
"We didn't do anything [Saturday night], we just laughed it off. Then I woke up this morning and thought what a cock-up that is I thought 'hang on a minute, that's actually really bad'.
"What's going on?"
He said the fact it was not just the one text, but two - possibly indicating the pair had the same contact number - was also poor, he said.
"It wasn't sent once, it was sent twice. And my concern is if it's happening to me what other bumbling mistakes are they making.
"Why are they sending out the private information of people's results for a start, secondly not once but twice and the third thing is, how many other cock-ups have been made?"
He said he did ring the 0800 number yesterday, but no one answered. He left a message.
"I feel extremely frustrated when I get a sense of the ineptitude who are running this show, and my question is, why have you got a Minister of Health, why has he got so many portfolios on his plate because this is when mistakes happen and this is one of them."
A spokesperson for the Northern Region DHBs (Northland, Waitematā, Auckland and Counties Manukau) said they were aware of the specific case and confirmed they had "resent the negative test results to the contact numbers they had on record for the intended recipients".
To protect patient privacy, the automated text message contains only limited information and a number to call if it has been sent to the wrong person, the spokesperson said.
"As is the case in communicating any test result, a process has been set up to protect patient information and privacy. This process is in line with the privacy policies of the Northern Region DHBs.
"If someone tests positive for Covid-19, they will receive a call from a medical officer of public health who will advise them on next steps."
The Northern Region had processed "hundreds of thousands of Covid-19 test results" and, occasionally, people getting a Covid-19 test had given them the wrong number by accident or it had been recorded incorrectly.
When a mistake was a made it was logged, an alert was then sent to the referring GP and/or community testing centre where the test was taken and then the person who had the test is informed of their negative test result.