You know what - that reminds me of something funny that happened to be with the Owlbear. In one run, I was talking to Edowin's siblings trying to goad them into fighting as fodder, and once I got out of the dialogue - I was immediately thrown into combat. The Siblings hadn't triggered it, but for some reason Astarion had walked all the way down into the Selune statue area and come up behind the Owlbear mother and triggered combat. I guess because of the running water you have to force him to walk through - he decided to avoid.
Did you have Astarion in your party during the encounters that forced combat? Was he with the group when this triggered or seemingly misplaced?