Car alarms and heavy trucks still send a shiver down his spine.
"On Valentine's Day, I took [my wife Janine] to Wellington for the night. We were having dinner at a restaurant and a loud truck went past. We both looked at each other; that split second of fear. But then you realise it's just a truck."
Feelings of panic and uncertainty bonded Christchurch residents that day. They are in a club none of them want to belong to. "We were like lost children looking for a grown-up."
He tells his kids everything is going to be okay, but admits - after more than 5000 aftershocks - he doesn't know if it will.
"I keep thinking, will we ever be normal again? ... We have one foot at home, one foot at the airport."
Gunn and his wife established a charity website - adoptachristchurchfamily.com - to help families put their lives back together. Donations are anonymous and vary from $10 to thousands of dollars.
"So far we've raised more than $800,000 and helped over 700 Christchurch families," Gunn said. Money has come from across the globe.
An email is sent to donors telling them where their money has gone. Most requests have been for food, household items or temporary accommodation.
One child wrote to Gunn wanting a bicycle for his father. "He said, 'could we have a bike for Dad because he doesn't have a car and wants to go to work'. It was just an ordinary dad trying to make things normal."
You can hear the heartbreak in Gunn's voice. He says knowing people give a damn counts enormously.
"Nothing matters any more. I've fallen out with people over the years, and then I'd get a text [after the February earthquake] saying 'hope everything's okay', and it's all bygones."
MP on the run
An observant Diary reader clocked Auckland Central MP Nikki Kaye running down Victoria St on Friday afternoon, handbag clutched under her arm.
"She was really gunning it," our source said. "I was sitting in traffic by Les Mills when I saw Nikki sprint by. She wasn't cracking a sweat. She looked glamorous, whizzing past in her tight, little black dress."
The MP was in a dash to get to the RadioLive studio in Auckland's Ponsonby Rd for an interview with Paul Henry and her Labour counterpart, Jacinda Ardern.
Kaye told The Diary she realised she wouldn't make it in time after getting stuck in Central Auckland traffic in Queen St.
"I only made it as far as Franklin Rd. Unfortunately my iPhone ran out of battery, so I had to dash into a constituent's house and use their phone to ring in to the studio.
"As far as interviews go, it was a workout - literally."
Mayor and ministers at odds already
The Beehive and Auckland Town Hall have started their relationship this year on the wrong foot. Last week, Mayor Len Brown proposed a raft of taxes and tolls to fund his vanity projects, but some Government ministers wasted no time shutting down some of the mayor's legacy options.
The mayoral office will not be happy with the Government sticking its beak in, particularly after Mayor Brown assured Aucklanders that Wellington would keep out of the debate on his alternative funding options until Aucklanders had their say.
Plenty of people think the mayor's toll proposals are political suicide, while others are saluting him for confronting Auckland's eye-watering funding shortfall.
Whatever the take, rest assured Prime Minister John Key will be keeping his distance until the public forms a view on the proposed taxes.
Jackson's secret deal with Spielberg
Sir Peter Jackson will direct a Tintin movie sequel immediately after he finishes work on The Hobbit, Steven Spielberg said in an interview with Total Film.
"Peter's doing it. I wanted to do it, but Peter has to because we made a deal. I said, 'I'll direct the first one [The Adventures of Tintin], you direct the second one'."
The Hollywood heavyweights are making a trilogy of Tintin movies one at a time after Paramount studio baulked at the prospect of financing three films upfront, the Guardian reported.
However, Spielberg won't reveal which books the sequel will be based on.
"We have completed a story outline now. We have a writer on it. I'm just not declaring what it is. It will be more than one book, but no more than two."