PM's Brexit vote hesitation may haunt her
Unscripted but uncontroversial - the prime minister had been safely navigating a radio phone-in.
Then a quiet, excellent booby trap question was laid by the interviewer, Iain Dale, for the prime minister.
She had, as she has said many times, balanced all the evidence and looked at all the facts to come to her original conclusion about backing Remain in the referendum.
She had been lobbied by both sides to pick them, but in the end went for the doomed side of the status quo.
Would she, more than a year on, stick to that view? Or is she now a convert, a true believer to the Brexit cause?
If there were to be another referendum, what would she do?
Now, to the mind of someone like Theresa May who is known to take time to make decisions, to call for evidence, answering a hypothetical question about something that isn't going to happen is perhaps the daft kind of game that journalists like to play from time to time.
The point of those kinds of questions however is to probe a politician's instincts.
In sticking only ever to purely factual answers it tells us little of their character, little of their thinking, little of their instincts.
Fairly or not, Theresa May's hesitation in giving her answer on this hypothetical question will give pause for thought to those who harbour suspicions of her real commitment to Brexit.
And her "open and honest" answer, which refused to come down on either side creates the strange situation where the prime minister appears unwilling to give full-throated support to her government's main policy.
Of course, as she has said countless times, we are leaving the European Union, "Brexit means Brexit" - soundbites repeated ad nauseam.
There is no question that she is fundamentally committed to the objective she has set for the government, determined to carry out the policy and Downing Street sources have suggested it would be ridiculous to say her comments raise doubts about whether she will deliver Brexit.
But the refusal to be categoric on whether she would choose this set of circumstances was telling.
It's easy to see why she wasn't willing to answer.
She likes to talk about things that are real, rather than imagined.
I remember, in the referendum campaign itself it took months - yes, months - to persuade her to give us an interview about why she had come to her conclusion to support Remain.
And most importantly perhaps, she is the kind of politician who believes in doing what people have asked her to do, rather than blindly pursuing what she believes herself.
In that sense, in many areas she is not a "vision" person, not a policy-pusher either.
And for some, that's an advantage, one Brexiteer told me today: "She is the best person to be the Boss because she is an administrator."
It's not about imposing her views on her party, or the country (of course, she doesn't have the majority to do that in any case).
But her hesitation tonight may haunt her - and it's a judder that Number 10 could well have done without at a time when they are trying to rediscover the ground beneath their feet.
At the very least, it's a question that she will be asked, again and again.