bestbuy has been known to put opened products back on the shelf provided they appear to be NIB quality (non defective, not tampered with). normally its a good idea to check to see that the factory seal is intact.
as far as it having a plastic cover or not...impossible to tell unless you get some pictures of an "unboxing" like some review sites have.
if it looks brand new, has absolutely zero micro-scratches or fingerprints then you're probably okay. if you are that OCD just return it and buy one at a different store and if it arrives the same way its NIB.