Paul, I apologize because this is unrelated, but maybe you can help me out here:
In recent years, there have been a lot of retaliation for hard, yet clean hits. When the hit is made, the referee's arm is down (they are clean hits). However, once the player is fought, or retaliated against, there is sometimes a 2-minute minor for charging/roughing. The best case of this would be Braydon Schenn's hit on Paul Martin and subsequent cross-check by Asham.
http://www.youtube.com/watch?v=yoaktQ0xQSM
The referee is looking directly at the play as Schenn makes the hit. His arm is down, and the play is not blown dead as Philadelphia has the puck. Asham cross checks him, and the referee immediately raises his arm and the play comes to a halt. Yet, on the play, Schenn was given a 2 minute penalty for charging.
This is just one example, but I've seen it numerous times. Did you ever call a penalty "after the fact" like this and, if so, why?