Off the California coast just a few hundred yards, or even closer is the whales' seasonal migratory path.
I have seen them from both shore and from a boat in the water, but getting in their way in kayaks seems quite foolhardy.
Maybe this particular whale was "sending a message" of "get the bleep out of our way."
Porpoises are also seen close in offshore in California, and may come alongside a boat for instance.