A Magic:The Gathering pre-release kit [Amazon] is about $25 and contains six booster decks and a D20. What would you think if you bought 14 such kits from your local game store, received not one good card, then bought another kit at a grocery store and spotted that it was shrinkwrapped differently?
"It feels a little off"
The "fake" boxes have rougher cellophane but a more precise seal: perhaps what you'd expect from a consumer appliance designed for preserving food.
The cards themselves are held inside plastic foil booster packs which should openly as cleanly as a bag of peanuts. With the suspect decks, though, the art and wrapping material delaminate as they're opened, and leave visible superglue residue. Oh my!
The store at hand is left unnamed, but the serial numbers of the decks are posted, so the manufacturer, Wizards of the Coast, will be able to figure it out. Note that there's always the possibility that the store is being framed and it would be very easy to do so.
I figure at $25 for a deck and a die or two, there's plenty of margin for some basic security measures such as, say, watermarked shrinkwrap or air-sensitive paint dabs.