Sarcasm and my Toddler

Yes, I'm a proud parent. Not only does my Baby m ALMOST say "mama", but E has such sophisticated conversations that I sometimes forget I'm talking to a toddler. I have to be very careful about using sarcasm with her, because she takes everything at face value...yes, I know, she's two and a half, but I really do forget. Here's a conversation from last night's dinner table...

E: Mommy? What are you going to be for Halloween?
Me: I'm going dressed as a mommy.
E: (pause) What?
Me: I'm going to dress up as your mommy. That's what I'm going to be for Halloween.
E: But where's your costume?
Me: This is it (pointing to my tee-shirt and jeans). Do you like it?
E: (long pause) Yes.

Now that I think about it, perhaps she was being sarcastic right back at me!