My guess, helped along by Soundguy's thoughts RE the blades being bent during shipping due to blocks under the deck - If enough force was applied to bend the blades, surely the spindles are crooked. Think of the leverage gain you'd get over the length of the blade.
And over that length, the spindles wouldn't have to be visibly crooked to make a large difference in height at the tip of the blade.
Whatever the problem is, I'm looking forward to how they explain their way out of the dumb comments they've made!
Good luck.