I would find this misalignment unacceptable on a Premium/LE machine; you are paying a premium price for a better than average machine and that should include the artwork on the playfield! If this was a standard edition playfield, I would still question how this passed QC but wouldn't pursue it with nearly as much vigor as I would on a premium or LE as it's a completely different market; what will pass as acceptable for a standard edition is just not acceptable on a high end pin.
Hopefully your supplier and Stern does right by you, as you deserve better.