The inheritance sounds a bit informal, but
- IF the aunt was the executor
- AND she distributed the gun according to the decedent's wishes
THEN it sounds like it really was an inheritance.
If that were the case, neither California nor the Feds require an FFL to be involved, and it would have been entirely legal to just pick up the gun and bring it to CA - the Roster has no influence on inheritance.
Proper paperwork in the case of inheritance is to file the OPLAW form, http://oag.ca.gov/sites/all/files/pd...rms/oplaw.pdf?
OTOH, if the aunt was the beneficiary and just gave the gun away because uncle wanted it that way, it would NOT have been an inheritance. Then sigcurious's post applies.