They're ALWAYS watching and it's deeds not words that matter. You can't say "Don't lie" then cheat on your taxes.
I read a study years ago that showed that it's the little, day-to-day things that matter in parenting, not the big ones. It's the weekly walk to the bakery and not the trip to Disneyland that kids treasure when they are grown.
There are moments in parenting that come back to haunt me (a couple from over a decade ago). The important thing is to do what you did and try to recover. Did you tell him you made a mistake? I follow you on Twitter but I'd never read your blog until today. Going into my feed reader, pronto!