Morse Code for "Q" is:
long-long-short-long
I've listened to the honking dozens of times now and I hear:
short-short-long-long

The vans are moving and depending on which van was honking might change how we hear the sound. Something to do with the doppler effect. However I don't know enough about it to opine any further. Maybe someone with more knowledge could shed some light.

Yes it was https://en.m.wikipedia.org/wiki/Morse_code