In Arducopter 3.2 using APM 2.6 there is a change in buzzer behaviour (from 3.1.x) when arming the FC.
The first time the FC is armed, after power up, the buzzer will beep a few moments before the propellers start to spin. This is a good warning, although I think the delay between the beep and motor start up is too short.
However, and this is the problem; if the FC is disarmed then on subsequent arming the buzzer will sound at the precisely the same time as the motors start to spin. This is potentially dangerous as the warning is sounding far too late.
The symptom is completely demonstrable on my build. If you need to see a video of it I will prepare one.
Please consider this as a bug for fixing in a near point release of the code.