IMO it is as qrtxian suspects -- it is called a DRAW even if it does resolve in the tiebreak when damage figures ramp up, i.e. despite the fact that one side wins eventually, it is called what it is at the onset of tiebreak.
Rational: Many shots have scored a 0 (787 shots total only 93hp, *whack* to say the least), and then out of the blue 13hp with one shot! That doesn't happen without a rule shift (reminds me of good old "Sudden Death" in Worms2).
However, the "DRAW" title is a bug. There's no denying.