Bringing this back around to the OP.

It looks like all of the retailers have raised the price back up as of yesterday, maybe even Thursday. Given that this wasn't a prolonged price drop, either they cleared the inventory they wanted very quickly or there was a glitch in the pricing at Amazon and B&H/Adorama followed. Given that the price reduction was $300, the same as the current mail-in rebate, I am thinking someone mistakenly applied the mail-in rebate as if it were an instant rebate.