Several posts on Apple's support forums suggest Apple is withholding shipments of a select number of Verizon iPad 2s. Details are sparse but shipments en route from China are apparently being called back to their destination.
9to5Mac was also reportedly told by a store employee that Apple has provided a list of serial numbers for Verizon iPad 2 models. All shipments from June 6 to June 11 are supposed to be scanned for these blacklisted devices. If any are found, they are sent back to Apple. This one store has already sent back 100 tablets.
From the description, this unknown problem apparently affects a handful of Verizon iPad 2 units. Neither Apple nor Verizon has publicly commented on this unexpected and unofficial recall.