They are surprised it happened again? Certainly, because after killing two people that whale certainly had its share and would never feel like doing it again... And those 10 other incidents from the same place involving attacks on humans totally didn't give any indication at all, either... Or claiming that the whale wasn't obeying that day and seemed agitated. There certainly seemed to be more than enough clues it might not be the smartest idea to go sit on the edge of the water and pet the huge, annoyed and carnivorous whale.