It is also possible he was around a lot of boys on his vacation and realized things like rough housing was fun and maybe there was a game or activity he enjoyed he hasn't done with your daughter. Maybe talk to him about his vacation and what fun things he did and you may learn even more or something you can include in the program. Glad you got the reassurance from mom. With the divorce the last thing the child needs is to be uprooted from what now is his most stable setting as both parents will have a place to live but not a home he knows.