"It's NOT a Bad Word"

Earlier this evening my sweet, little, 3 1/2 year old stubbed her toe and said "Oh HECK!!" We both turned around and looked at her. She put her arms to her sides and simply said "What? It's NOT a bad word, it's okay to say."

I then realized a few things:
1) I didn't know that she could be very logical about what she says or that she would be able to justifying what she says at such a young age and be so reasonable about it.
2) How to properly respond to a non-swear / swear.
3) Who on Earth taught her both the word "Heck", furthermore, who taught her and I quote "What? It's Not a Bad Word."


How did I respond? 
I told her, "Yes, you're right, that's not a bad word. Who taught you that?" She just shrugged her shoulders and said "I don't know..." It then lead to a discussion (some would call it a nice interrogation) about "Good" words and "Bad" words. So far, she doesn't know too many "Bad" words. Her definition of "Bad" contains words like, "Stupid", "Brat", then there are the kid "mean" words, such as "Poopy Head". Apparently "Heck" is on the Good List-Works for me. 

Looking Innocent