He explained further, but the only words I caught were "condemned" and "failed" and I began to panic. Not because of his "I could fix it but it would cost you, love" spiel, but because of the F-word. I have been in FE long enough for it to have become a pariah-word - a word which, if you tiptoe anywhere near it, makes alarm bells clamour and red lights flash.
Fail. My response is Pavlovian.
In FE, we don't use the word fail. We say you have not yet achieved. As you can guess, then, I have been following with some delight the ongoing controversy surrounding teacher Liz Beattie's suggestion at the Professional Association of Teachers conference that schools should replace the F-word with "deferred success".
Her opponents talk of political correctness gone mad and of the dangers of "mollycoddling". Life is hard and the sooner kids learn that the better.
Scramble up another couple of sooty chimneys while you're at it and learn the value of hard labour.
Liz Beattie was talking sense born out of experience and awareness. No one wants children condemned to failure. But no one is pretending that children can or should succeed in everything they attempt. What they need to learn is how to fail.
We are saddened by tragic cases of suicide among young people who cannot cope with the strain of succeeding, or who have failed in their ambition, but we may well be unaware of how many are quietly diminished by failure or the fear of failure.
As educators, we need to teach individuals how to fail, and to see it as simply an opportunity for reassessment, not just of the task, but perhaps of the whole situation. As educators, we are responsible for that learning so that it is not destructive.
The entrepreneur Simon Woodroffe understands perfectly that the fear of failure is the greatest limit on achievement. At the beginning of his career, he set himself a target of achieving seven rejections a day. A refusal, a disaster, counted as a step towards his day's target. He was taken aback by how many sure-fire refusals turned into roaring successes - from asking an apparently unattainable woman out on a date to securing a huge sponsorship deal.
"Deferred success" sounds like another very good way to encourage children to cope with failure - to pick themselves up, dust themselves down and fight another round. Don't underestimate them; they will know full well that a deferred success label is not the same as passing. But it certainly doesn't have the sound of a door slamming built into it.
In FE, we have grown accustomed to leaving the door open - but then FE has always been streets ahead in modular programming, continuous assessment and in the way that assessments are graded.
I am reminded of the Hippocratic oath - "first, do no harm". We educators should take that to heart, too. Further education has acted both as a safety net and as a highly progressive and successful model. I do not think learners who come to us have been damaged or diminished by their experience of learning. That's no small feat in this harsh world that is our education system.
But my plumber knew nothing of this. He took out an assessment sheet and began to tick boxes. "There's no way this is failing," I said.
"Deferred success," I told him. "Write that down."
Dr Carol Gow is a lecturer in media at Dundee College.