Thyroglobulin at 4.1

I had a total thyroidectomy back in the middle of january. I've had radioactive iodine done and the result were good. My doctor adjusting my dose of levothyroxine to get my thyroid levels down and it seems to have worked so far based on my blood test. However, I just got my tg tumor marker results and the number is 4.1. I know that the higher the number the worse it is. Every other test has been good lately and my ultrasound didn't show anything out of the ordinary.

Is 4.1 really high for tg levels?