Sobriety Checkpoints: why inflection is important

[da]

Last night I had a Quaker committee meeting. I carpooled with J., who lives in Waterloo. When we were getting off the highway at the south end of town, there was a sobriety checkpoint. I've never actually been in the car when one of these has happened (well, I was once stopped by a police-person in Ithaca, but that wasn't a checkpoint). The general model is certainly one I understand, but...

What I thought the policeman said:

P: Good evening. This is a sobriety checkpoint to find out have you had any drinks tonight.
D: OK.
P: ...

What actually happened:

P: Good evening. This is a sobriety checkpoint. Have you had any drinks tonight?
D: OK.
P: ...

P: Have you had any drinks tonight?
D: No.
P: Thank you, have a good evening.

See, with ambient noise, I didn't quite catch the middle part- and I heard a downward inflection at the end of his statement. It sounded authoritative and preambleish, but not questioning.

And I guess that's the difference between getting stopped at a sobriety checkpoint and getting stopped at a sobriety checkpoint; I had the sense to not continue the conversation and tell him he sounded too preamblish.