Car ran fine then wouldn't start, got a jump, now everything is fine again. What happened?

'03 Honda Civic. Last 30 mins of work I sat in my car with the A/C on full blast and radio on, like I do everyday (and of course the car is running). I stopped at Subway after work. The car was parked for 10 mins.

After the car would not start but the radio and dash board lights would come on, but it would not crank.

Got a jump from AAA.

Afterwards Auto Zone tested the battery and alternator, both passed.

I has been a week now and no problems.

What the heck could have happened?

Dirty or loose cables