Dive-Right-Ins

I was having a conversation yesterday with a quizzing acquaintance, and we covered a lot of quiz related ground, as we often do, on phone cheating, current TV likes and dislikes, displeasure over the cancellation of University Challenge for the duration of the Olympics, I'm sure you know what I mean, all the usual sort of things. Then he told me about a great 'dive-right-in' question he was asked a week or two again.

For the uninitiated, a dive-right-in is the question which seems to have such an obvious answer that you dive right in with the answer without even thinking, and indeed you never give it a second's thought until the answer is given and you realise that you were wrong. It's probably easier to give a practical demonstration rather than keep trying to describe it , so here's the question :-

In the Squeeze song "Up the Junction" at what time does the woman in the song give birth to the baby ?

If you answered, "4:50", I can totally understand why , after all : -
"This morning at 4:50, I took her rather nifty "
- however the lyric goes on -
"down to an incubator, where 30 MINUTES LATER
she gave birth to a daughter. "
So the answer is actually 5:20. Really well thought out question, I thought.