Did you cast "Friends" or "Charm" on anyone? There seems to be a chance for NPCs to turn hostile when the effect ends (which is intentional I think).
It's possible. I probably used Friends when persuading the Druid leader to let the girl go but that shouldn't be reason enough to have her announce that I have "betrayed" them and order every Druid in the grove to attack me. I bet I also used Friends to persuade the two Tieflings that captured the Gith companion to leave but then they also attacked me after the conversation. I don't mind some consequence for casting a spell on someone but I hardly think it should cause everyone to immediately want to kill you. The whole point of the spell is to help you reach a peaceful resolution so making the target attack you after the conversation can't be good.
