The docking connector isn't really a common link between ALL of the outputs, as the ground is only common to a stereo pair, not to all four outputs. It is possible that both ground sets (or all four signal sets) could snap off if over stressed, but the chances of them reconnecting themselves later are slim to say the least.

Internally, the audio is common to the car mount and the in-home jacks right up to the final differential pre-amp stage. A loose pre-amp board could cause the fault, but as I said before, I think it's unlikely.

I'd be inclined to wait a while and see if the fault recurrs.

Rob