Yes, I think so, but I've never had problems with mine. I would guess virtually all pumps would have a similar arrangement, perhaps the Leo is arranged to cut out at lower temperatures than others.
I think the reason for cutting out is trying to pump oil that's too thick. The motor will be working harder, drawing more current, revving slower and therefore not have as much cooling. Hence the note about not pumping high viscosity oil.
When you consider its intended duty is as a water pump, it's not unreasonable they sometimes cut out pumping cold veg oil!
