Not sure if this is in the right section, please move if needed.

Tonight DS2 (7yrs) was told to have a shower, he made it as far as getting undressed and ended up sitting on the couch naked. I told him to quickly go hop in the shower as DD1 (19mths) was around and she didn't need to see him naked. Somehow they both ended up in the kitchen with DD1 touching his penis. I growled at him to get in the shower and said DD1 is not to touch him. He went into the bathroom, but came straight out and stood in front of DD1 and let her touch his penis. I don't think he realised I was right there.

Alarm bells went off and I growled at him to get in the shower, and then he was to go straight to bed as he'd already been warned about that behaviour. In hindsight perhaps I overacted? I don't know. Is this in anyway normal? Should I be concerned?

We have the book "Everyone's got a bottom". We haven't read it for about a year. I got it out for him tonight and said he should read it again. He threw it across the room.

How do I follow up from here? And advice or suggestions most welcome. I hope my growling hasn't done damage, but I was very shocked and went into overdrive to protect DD1 I guess.