Nudist Mom with a question

Hi all My name is Cindy and I have never really been into forums or social media of any kind so bare with me.   I looked up this forum to seek advise about something.  My husband introduced me to being a nudist before we were married, that was 12 years ago.  We are in home nudists mainly because where we live there is nothing really around where we could be otherwise.  Here is what i am asking about.  We have a son who was born a couple of years into our marrage and we decided to raise him in the smae lifestyle. To make a long story short recently I have noticed him trying to hide and masturbate as he watches me.  This has happend at least 2 times now that I know of and honestly I don't know how to talk to him about it.Thanks in advance for ideas.   Cindy