UGH .. so sorry this is dragging out for you ... keep us posted ... would have been nice to have reassuring news right away!
C~
I had my full body scan a week after my RAI and my thyroid bed was lit up like a New Year's party in Time's Square! They said it was a "significant" amount of uptake and I would probably need another scan (and possibly RAI) this coming year. The way my endocrinologist explained it to me was I still had quite a bit of thyroid tissue in the bed and, because my TSH and thyroglobulin had been increasing, I had a recurrence of cancer (three years after surgery).
If I remember right, you're not that far out of your surgery, right? No surgeon can get all the thyroid tissue removed. Chances are that's what is uptaking the RAI and they just want to do a second scan (after you've "cooled off" a bit) and ensure there is no uptake in any other surrounding tissues, lymph nodes, etc. Don't panic, it's pretty normal.
When I had my body scan in February, they called me a few hours afterwards and asked if I could come back on Monday. So all weekend I was freaking out that something major was wrong. I tried to reassure myself that my surgeon who was a very thorough doctor did the best possible. Went to get the scan on Monday and was told the camera they used on Friday was new and wasn't working right and they wanted to use a different camera. They ultimately told me there had been some uptake in the thyroid bed, but everything was good and they saw nothing out of the ordinary. Maybe you situation is something just as inocuous.