Board Thread:Speculation House/@comment-3146930-20140612004954/@comment-24219008-20140614161022

Unless Penny was created (assuming she's an android) right around the time Weiss started attending Beacon, because it seems like she hasn't really had much contact with her father or the SDC since her arrival (that we know of). Then it would make sense that she wouldn't have recognized Penny when she ran into her in Episodes 15 and 16.