There were a couple comments like this from people who have bought batteries from Amazon. BEWARE:

My D51R went bad after a month. Optima says take it back to whom you purchased it from. I said Amazon, they said "oh no." Optima will not honor the 36 Month Warranty and Amazon said I'm stuck because I can't ship it back -it's hazardous material and it's beyond the 30 day return policy. "We are real sorry, but there's nothing we can do." So if you are going to buy a battery from Amazon - you will be stuck - without any remedy. Join the suckers club with me.