Recognize that KBB values are absolutely worthless. KBB trade in is about what you should pay for a dealer non-cpo.

Get a PPI done, even if they just did a CPO. Dealers lie, you have no recourse once your buy it.

Edit: Ask the salesman for the records, he will probably say no. You can ask to see the CPO checklist- THAT they are required to provide to the buyer.