I have run into guns that have sat in the system for yrs , with no calls, letters from Fire arms. Did one for a estate that was 1970's.
Had a gun show up in my name from 1980,s that I had sold, transfer never completed at the other end.
There nothing with this where you need to worry, as long as the owner will call the transfer in simple.
Only problem that could crop up is if the cobra is a 12-6, than things can go south, if he let his RPAL run out .
P.S. Why the hell would this not have been taken care of before he left? and tossing the paper work is not a big deal, but not smart.