Not good. If true, this means there is a possibility the gun store sold it to him in error. I hope they have good liability coverage.
Not true. If NICS does NOT deny him, the FFL is under obligation to release the firearm to the person that filled out the Form 4473.
If the FBI calls back later and says, "Wait! He's a felon and should have been denied", I tell them, "I'm following federal law. I HAD to release the gun since you goofed up. Now you get to go and get him. Be sure to bring my gun back to me personally". Click.
When you don’t have a CWL in states that have permission to bypass NICS checks, the gun is held until a passing confirmation by NICS is given (an actual number IIRC back when I didn’t have a CWL). Even before this, the Form 4473 is scrutinized. If any of the trigger questions are wrongly answered, the dealer won’t even get to the NICS check.
Given this is the FBI, I’d want to see real, I could touch it, proof.