I understand wanting to let the other party know first, but I don't think it is bad form if you still fill the need to bring it up. I had a similar experience when I first started. CA did something way beyond inappropriate but since I was new and didn't want to make waves, I just let it go. If we had Pro Standards back then, I would hope that I would've made the call. Later I found out that something similar had happened to other co-workers and I put some partial blame on myself for not saying something earlier. If it is still on your mind after the trip, my suggestion would be to make the call. It may save the persons job if they can have that discussion with Pro Standards vs a CP or disciplinary board.