Yes.
Unless you had RAI as well, you probably have some bits of thyroid left. You may be getting a little hormone there.
I had RAI rather than surgery, and my Endo said I may not need more than 100mcg of Synthroid, but I don't think so. I'm taking that now. I'm guessing maybe 125 or 150 when my gland finally dies. I think she told me that in case I end up with a third of a thyroid left.
A few people can get by on 100mcg, but most people who had TOTAL ablation take between 150mcg and 250mcg.
Thanks for your comments. Yes, I have had both lobes of the thyroid surgically removed and an untrasound to see if any remained. I have no idea why I would have a low TSH on 100 mcg. of levothyroixine. Sometimes I think medication dosage should be based more on body weight than the result of thyroid tests. For some people(myself included) thyroid tests can be misleading.