As stated below, it's because in some states the state acts as the point of contact for the Feds, and in other states the dealer has to call the Feds directly. If the state is the POC, they can decide that anyone they have already issued a CHP to is worthy of getting a pass.
NICS Background Checks
The FFLs have the following three methods of performing background checks depending upon the state in which the FFL is conducting business:
1. In states where the state government has agreed to serve as the POC (point of contact) for the system, the FFLs contact the NICS through the state POC for all firearm transfers. The state POC conducts the NICS check and determines whether or not the transfer would violate state or federal law.
2. In states where the state government has declined to serve as a POC, the FFLs initiate a NICS background check by contacting the NICS Section for all firearm transfers. The FBI conducts the NICS check and determines whether or not the transfer would violate state or federal law.
3. Finally, in states where the state government has agreed to serve as a POC for handgun purchases but not for long gun purchases, the FFLs contact the NICS through the designated state POC for handgun transfers and the NICS Section for long gun transfers.
Each state decides whether the FFLs in its state call a state POC or the FBI to initiate firearm
background checks.