is not very sensitive and specific for diagnosis of typhoid
It can be negative in a person who is suffering from typhoid. A single titer of 1:160 for 'O' is suggestive of typhoid. TH antigen titre more than 1:160 indicates past infection or immunity to the typhoid.
A four fold rising titre is more suggestive than a single raised titre.
Raised titre may take 3-6 months to become normal.
Now after going through your different values it seems that your baseline value is TO 1:40 and TH 1:160. Now to see whether this TH titer is due to past infection or immunity get a IgM and IgG
level done for S.typhi.
As you have completed your treatment and you are clinically improved, no need to worry.
In any disease it is better to treat the patient rather than lab values.