Rigors without illness after tetanus toxoid. allergy?

Maybe: Allergic reactions to tetanus toxoid are uncommon, but they do occur. True rigors (hard shaking chills) usually occur with episodes of bacteremia (bacteria in blood stream), and one possibility is that the multi-dose vial used for the vaccine was contaminated, or that the injection was not sterile, or that the lesion for which the vaccine was given was transiently infected.

Abnormal: A rigor is an extreme reaction associated with high fever and shivering etc. It is an illness in itself and indicates that the patient over-reacted to the toxoid. Whether you call it allergy of sensitivity is immaterial. The toxoid should never be given again.