Never ending pumping

[hinten]

Dropped my boat in the water today and parked the H2 and trailer.
After three hours on the water my wife gets a call and we have to leave so we pull the boat back in and I walk to where I parked the car. As I am getting close to my H2 I can hear the air compressor in the back going. The H2 is locked, keys in my hand. I am thinking 'Oh, oh!' Three hours continous air pumping.
So, as expected, I can barely start the car, the battery was almost dead.
Once I started the H2 it says 'Service rear air compressor' but I had to get the boat out of the water. A couple of minutes later the warning disappears and the pumping stops haven't seen it since then.

I remember reading about something similar. How can the car do anything when I pull the master switch (ignition key)? Who thought it was a good idea to let the compressor run after I lock the car and why did it keep pumping in the first place?

The is not the towing vehicle I thought it would be...