Parenting fail?

About a week ago, I was cleaning up the kitchen after dinner, and Abe was finishing up his nightly after-dinner bowl of cereal.
"Mama, what does the middle finger mean?"

"Whaaaaaaat!?! Why are you asking me this!?"

"Because I got in trouble for it at school today. I didn't mean to! I don't know what it means, I just know it is bad. That's what my teacher said."

"Well, what were you doing with your middle finger?"

"I was just pointing at something, like this." He then demonstrates pointing at his cereal bowl on the table, with his middle finger.

"Okay, well, don't do that anymore. I know you didn't mean to do it, so that is okay."

"What does it mean?"

"It means you don't like someone ... it's like saying something mean to someone."

A few days pass (after of course, he told the story to Jake. One thing that kid did get from me was a guilty conscience. God love him.) Sam, Abe, and I were having our normal morning feuds -- fighting over what they would eat for breakfast, how many toys they could take for Show and Share, you know the drill. At one point, I was standing in the kitchen, coat on, all ready to go, yelling something to Abe along the lines of , "COME ON! HURRY UP! LET'S GO!!"

I hear his little stomping footsteps climbing the stairs and then the words that rang loud and clear:

"Ughh, I am coming ... MIDDLE FINGER!!!"