I had this happen several times with both Gale and Lae'zel, and other people reported it with other characters.
Although I am not sure if this is totally consistent, It seemed to occur when I went to the camp from the map option when I started in the open air. For example, I did a quicksave in the cellar of the "search the cellar" quest after retrieving the Necromancy book. I was able to go to camp through the Map option normally at that point. However, if I restored to this quicksave and then did nothing but go out of the cellar with my party, attempting to go to camp caused an attack (from Lae'zel that time). Also, when I killed Gale in camp on one of these occasions, I was unable to complete the resurrection ritual. I got to the point where I received the resurrection scroll, but was unable to select the dead Gale as a target.
This is definitely a bug.
