It's certainly possible, someone could load the machine with the wrong labels.. my hope is that it would be very very slim odds that something like that could happen and no one notice.
The likelihood of it happening is pretty high (s*** happens/human error etc), in theory if you have a strong QA program then the odds of that mistake making it out of the building should be almost zero. But you never know. We've had labels go on upside down before, thankfully none of those made it out into market.
Could also just be a bad batch.. that happens too.