I would be surprised if regen braking caused a issue at the rear. As it is handled by the electric motor, which is in the engine bay.
Other than the above, and just because you live in the warm, does not stop things from corroding. Hot day & cold nights = moisture on metal surfaces. Moisture on metal surfaces (especially brake disks) = corrosion.
I would take it back to dealer and tell them, could be a issue with brake sticking or pads glazing over, which as I see it is going to be a big issue with hybrids as you do not use the brakes as much.
I'm making a conscious effort now to actually use them, rather than rely on regen to slow me down.