How does it feel when you ride it? Can you reach the brake levers comfortably with your elbows slightly bent? The shop should not sell you a bike that doesn't fit you--did they put you up on the trainer to take a look at the fit? Not a whole professional fitting (although that would be ideal) but at least an educated look other than you just taking a spin around the parking lot.

Hopefully the bike fits. If it doesn't, you might consider returning it. Riding a too-big bike is uncomfortable and you won't want to ride.