Would it not cause problems, he asked, for people in physically demanding jobs to be required to work longer and to possibly find themselves having to change employment late in their careers?
The question was most directly addressed to Labour candidates Clare Curran and David Clark, given their party's policy of raising the age of retirement to 67 years.
"By 2050, the population of over 65s in New Zealand will have doubled," Ms Curran said.
"This is a serious issue, and we need to address it now.
"We [Labour] believe in providing the country with long-term solutions."
Dr Clark backed up her comments, saying "this Labour Party is willing to take on the big issues - muddling through is no longer possible".
Labour's policy included provision to provide support for people in physically demanding jobs, should they need to retire earlier, he said.
National Party candidate Michael Woodhouse said a retirement age of 65 years was affordable if two things happened - restraint in spending on other areas and a reduction in benefit dependency among younger people.
Restructuring the New Zealand economy was the key to the country's ability to provide for retirement in the future, Warren Voight (Democrats for Social Credit) said.
Act New Zealand regarded superannuation as "a social safety net", candidate Guy McCallum said.
"Our policies are there to strengthen the economy, but there should also be superannuation there when you need it," he said.
The Alliance believed in phasing in retirement, depending on the nature of people's jobs, South Dunedin candidate Kay Murray said.
"We would increase superannuation to 72.5% of the after-tax wage," she said.
Fellow Alliance candidate Victor Billot pointed out that no-one could predict what the world would be like in 2050 and New Zealand needed to restructure its society to reduce working hours and increase science and technology.
He was unimpressed by the concept of increasing the retirement age.
"Could it be that the people who own everything just want more and more of your work?" he asked.
The Greens' policy was to keep the retirement age at 65 years at this time, although it was "important to have a conversation about how we will transform the economy over time so older people can have income to sustain them", co-leader Metiria Turei said.
"There is a bigger conversation about how we reduce the gap between rich and poor and we must have it."
The United Future policy on the retirement was a good middle ground, candidate Peter George said, as it offered a choice between retiring at 60 or 70 years.