Wouldn't one possibly get problems when Leds are driven for longer as a few mS ?
While testing/programming, they could... be lit much longer.
9 leds on, sinked by one pin seems a lot to me.
A circuit I've used came from Ledstyles.de, it's in German, non C++ and it uses a smaller brother, the attiny2313. It uses 3 transistors to sink the current, but the rest... is basically the same. http://www.ledstyles.de/index.php?page=Attachment&attachmentID=5162&h=14fd27d042c0853320f7f045e11838b113fe8373
Link to the complete article :http://www.ledstyles.de/fpost99870.html#post99870