Thyroglobulin Level Elevated After Thyroidectomy and Radiation

I just talked with the nuke medicine doc. He told me my body scan came back "relatively clean" with a few spots in my neck. He said he was a little concerned because my thyroglobulin levels were high. I had the radiation about a week and a half ago, surgery 6 weeks ago and body scan 3 days ago.

What does this mean? Is the cancer still there or not?!