It happens ALL the time...for mainly PlayStation of all platforms. No one seems to care about the gap between shipped vs sold when it comes to Nintendo. Even with PS5 being sold out it can take several weeks for consoles to ship from the manufacture to retailers. So there is the gap.
My guess is the Switch is doing so amazingly well that hardcore Nintendo fans don't feel a need to make a fuss about it. It might happen less often with the PS5 once its sales pick up.