Anything that's mass produced can have a defective batch. I'm big on consumer rights and if that's the case take it back to where you bought it. They should exchange it.
You think a defective rotary blade is bad? I was a Phlebotomist for years and on rare occasion our HUMAN needles had a flaw of a miniscule "barb" of left over metal on the tip. You KNEW IT when your patient almost keeled over when you retracted your needle. You almost needed a magnifying glass to see it...but..it WAS there.
Anything that's made by a machine can have imperfections. Especially mass produced things.