Congrats on your approval.
I just got approved this week too, so I know how giddy it makes you feel.
More than likely the people at your doctors office just submitted it with the wrong insurance code. It happened a week or two ago with another member, and she was approved for the lap band instead of the gastric bypass she (and her surgeon) wanted. It just needs to be resubmitted by the doctors office, and it can get fixed. Not a problem, it'll just take an extra couple of days...definitely not worth the extra pain and recovery time of having an open procedure if there is no medical reason to do so.