Pregnancy test after miscarriage

My miscarriage began around October 19-21st. I am sure I passed the bulk of everything on the 21st. Well, I had tests every week to ensure my levels went down. They started at 11,000. On November 9th, the levels were in the 100s, 190 maybe? I cant recall..so Dr told me I should be good and not to come back. I hadn't taken any pregnancy tests until last night. Then, I take one (it being November 27) and it was positive. Can HCG still linger on that long? I was sure it would be gone since they were so low early November. I also stopped bleeding around November 8th. Any thoughts??