Selling Property as an S-Corp

A few months ago, my company (S-corp) sold a piece of property to another guy and his business partner. My accountant informs me that since I sold it before January 1, 2017 (5 years of ownership) that I will owe penalties unless I get a signed letter from a real estate agent stating his/her opinion of the value of the property. My question is: is there any consequences of a real estate agent writing me this letter? Thanks in advance.