Car battery needs replacing on 2-year old car

What is your question?

The battery went dead on our 2008 Highlander Hybrid, which we bought less than 3 months ago from a dealer. car is driven on a regular daily basis, and we live in southern New England, so not cold this time of year. Dealer says we need new battery. Should this happen on a 2-year old car with 35K miles on it?