I would doubt that it was NOT intentional. If they weren't trying to use the original coupon to continue to lure people into the store, they would have sent out a retraction email so people would know not to come in expecting to the use the coupon. Instead, they've posted signs that you can only see AFTER you are at the store. Bait and swich at its finest.
That wouldn't help .. the VAST majority of the customers didn't get the coupon in the email, they got it from other sources online. They posted a correction on their website. So no its not bait and switch.