Saucers will receive an out event each time they leave the game world (the screen, in Saucer Shoot). There is nothing functionally different about a saucer leaving the screen on the left versus the top. To verify this is happening, reduce your code to a small case (e.g., one saucer), have it going up, and check via writeLog() messages in the eventHandler().
<p>I'm guessing you have some other logic issue in the event handler where the OUT_EVENT is received, but is being otherwise ignored. Put a log message write at the top of the eventHandler() to print event type for your 1-saucer test case above. Then, trace your code carefully down. You can send us (me + TA) your Saucer code if you can't find the problem.