Is it normal to experience heart palpitations, hr of 100, and dizziness when tapering prednisone by 1 mg? o

Palpitations: No. Experiencing palpitations is not normal. About 1-2% of patients taking stroid therapy reported palpitations as side effect. Some times prolonged steroid therapy could cause cortisol deficiency, which could lead to hypotension; tachycardia (rapid heart beat) could be a reflex response. There are multiple other causes for tachycardia and palpitations. Talk to your physician.

Unlikely: It is very unlikely in the situation you describe.