I think their numbers are rebounding back from a low in the 1970's-80's and they are basically re-inhabiting the territories they once inhabited.
Since there are more sharks, the big adults who frequent the well known feeding ground hotspots protect those spots and chase the up and comers away. The up and comers have to find new feeding ground and that's (I think) why we're seeing more in areas we're not typically used to seeing them.
Same thing with birthing grounds. The typical birthing hotspots are becoming overcrowded, so new (to us) birthing spots are being used. The young tend to follow water temps, so if it remains warm year long, they are happy to stay......like when the warm blob was around the CA coast for a few years. If the water gets cold, I think they head south to something more comfortable.