Does my son need professional help

I have a son that is currently 5 years old.  My former friend used to keep my son while I worked. She has two girls that are 5 and 7.  About a month ago I found out that my 'friend' caught her 7 year old getting my son naked in the bed.  She also informed me that the 7 year old had been molested a few years before.  I was very upset and questioned why she didn't watch our children better than that.  Instead of totally reprimanding my child because I didn't feel he had done anything wrong, I told him that if anyone ever touched him then he needed to come tell me.  He agreed and nothing else was ever said about it.  I refuse to let my son go to their house or even play with them anymore.  Since then I let my son go to my bestfriend's house and he proceeded to do the same thing with her 5 year old daughter.  It concerns me now because I don't want this to be a pattern for him.  My bestfriend is very upset over the ordeal, as I was when it was my son. However she has said really mean and hateful things to me such as my son is going to be a sexual predator and that there is something really wrong with him.  Well, I said that kids are curious and she said not at 5 years old.  Well, all the research I have done says that this is totally normal for a 5 year old.  I have since sat down with my son and explained that you do not look at another child naked.  You do not touch or be touched.  It is very unappropritate and if you do it again you will be in trouble.  Is this enough.  Do I need to seek counseling for my child?  I was working 2 jobs but have since quit one because I need to be home with my child.  He will not be staying with any other children overnight for a long time.  Is there something else I need to do besides supervise him more?  
Thanks,
Concerned Parent  :(

[margypops]

I think parents in general should supervise their children more young  children  are allowed with frequency to stay over, to spend too much time alone in bedrooms.. I think some curiosity is normal but your child is doing it to others maybe younger in my opinion this should not continue . So he does need you to supervise , as it has been repetitive maybe some counseling would be a good thing .good luck

[EVANIQUE]

I think you and your friend are overreacting. This does seem normal and i think you were hard on your first friend. At least she had the decency to tell you about it. you can't be there 24/7. just explain to the children about the appropriate times to remove clothes and that their "bits" are private. Just treat it as you would any undesirable behavour - they dont know its wrong unless you tell them - we are not programmed to feel shame at that age so i do think it was innocent. No "therapy" needed.