When Tsh Tests Indicate Thyroid Levels Are Low, Do You

When tsh tests indicate thyroid levels are low, do you increase or decrease levrothyroxine medication? My last tests indicated that my level was low and my doctor lowered medication strength. Have been taking medication for hypothyroidism for 40 years and that's the first time its been lowered when low. Has always been lowered when high. Is he confused? He says it's an inverse process. Thank you.