OK, bad marks for logic, you get.
A shortage is a good sign because it shows the product is popular? No sir, it doesn't show this, it just shows the product is more popular than the sales projector (?) suspected (or the distribution's screwed up).
Even with sales of 10units/year you'd get a shortage if you stock 5. And conversely, massively overstocking a popular product doesn't mean it's losing popularity, it just means overstocking.