Pre Authorized with a May surgery date and now insurance may want me to wait 6 months

I have been so excited because I just found out last week that my insurance pre-authorized the gastric bypass surgery.  My surgery date has been set for May 26th.  Today I receive a call from the hospital telling me that my insurance company may want me to wait for  6 months because I have only had this plan since 3/1/09.  The insurance company said that I may be able to get a waiver for the 6 month requirement if I can provide proof of continuous coverage which I have.  My question is has anyone experienced this with their insurance and if so, how successful were you at getting the waiver? 

Hi. I had a somewhat similar experience with my insurance. Not with coverage for WLS but one of the appts. I had to have in order to get approved by my surgeon for the WLS was to see a cardiologist.. Ok, then my cardiologist wanted me to get the nuclear stress test and the ecchocardiogram. Those things had to be preapproved with my insurance and when the lady at the cardiac center called them, they said I couldn't do them because I didn't have coverage before them (my insurance started Jan. 1st 09) but I have always had health insurance so all I had to do was give my current insurance my old insurance id number and info and then it was fine... So I think that's all you need to do. As long as you had insurance the day before you're current one started. Hope that helped.

Thanks for your response.  My previous insurance ended 4/1/09 and my new one started 3/1/09, so I had one month of double coverage.  Yes, I hope when they see that then they will approve my surgery date.