That is dominance behavior and should quieten down, I believe the top pig is the one that does the grooming, Sasspy kept doing this with Baby Widget much to Widge's annoyance. It settled down after a few days and the bum sniffing and ear cleaning has ceased... Glad all is going well. I am sure Haven will get more comfortable with the relationship over the forthcoming days, just keep an eye to watch for over stressfulness as you are doing, it all sounds positive.