Depends on your state law. In California, a buyer can rescind the contract 17 days after signing, without no questions asked.
The age of the house should be easily ascertained. You already have the appraisal report but did not read it in time. Who gave you the 30 year term? Can you prove the seller or his agent committed a fraud? Fraud in this case means intentionally falsifying a document. You must also prove the age of the house was a material factor that your decision to buy was based on. More likely than not it is not the case. You said the location was good, price was good, and inspection was satisfactory. There is nothing indicating that you wanted the house because it was relatively new.
Your agent is right. If you rescind, you are probably in breach and lose your earnest money.