Tickle Tickle, SLAP!

Flora and Scout were stripped down to their diapers this afternoon because it was SO hot (yes, I'm complaining about the heat in April). Scout was laying on the floor where I had been tickling his belly much to his almost-amusement. Maybe the heat makes Flora a little crazy (or maybe she's just a 1 year-old), but out of no where she ran up to us and slapped Scout on the belly! I opened my mouth to scold her for hitting her brother but was interrupted by Scout's loud giggles......I guess I'm being too gentle with my tickles. Is it wrong to hit your brother when he laughs about it?