That frequency of friendly behaviour, by design of the whale itself, is increasing. There is a learning curve and these animals aren't dumb. But Palm believes an adverse learning curve is just as possible. Hunting would have a huge impact here. Changes in behaviour can happen quicker than you think.
Whales cry in pain just like any other animal and whales in the vicinity hear that.
Grays in particular are very protective of their young. That's why commercial whalers knew that if they got into breeding grounds and harpooned a calf they could get mum, too, because she would come running. Under attack, they were anything but docile. Ford rules out a quick regression to such behaviour but warns that repeated pursuits could change grays' relationship with humans. He points out that while professional whale watchers police themselves, recreational boaters are not always so willing.