iOS Loses Touches?

I can't find anything to explain lost UITouch events. If you smash your full hand on the screen enough times, the number of touchesBegan will be different than the number of touchesEnded! I think the only way to actually know about these orphaned touches will be to reference them myself and keep track of how long they haven't moved.

Sample code:

int touchesStarted = 0;
int touchesFinished = 0;

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    touchesStarted += touches.count;
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    touchesFinished += touches.count;
    NSLog(@"%d / %d", touchesStarted, touchesFinished);
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self touchesEnded:touches withEvent:event];
}