Derek,

I loved the way you used a problem you ran into as an opportunity to educate the rest of us.

Also, in regards to e-mailing the apology, I've found that most people don't get angry if you make an occasional mistake as long as you take ownership of it and resolve it as you did. It's the person who makes mistakes and then tries to blame everyone else that makes people angry. Quickly admitting to a problem and then resolving it smoothes over a lot of problems.