Advice on American General Life & Accident Insurance Company

Has anyone dealt with this company before? My grandfather received a letter stating his life insurance policy is maturing in October of this year. The thing is, my grandfather passed away in 2000. We call the insurance company and they stated the beneficiary of the life insurance policy was my grandmother, who passed away in 1988. I just found it odd we are now hearing of this insurance policy.

My questions are: could this be a fraudulent claim(Someone stole my grandfather's social security number). How long usually does an life insurance policy takes to mature? I find it odd that my grandfather would take out an insurance policy so late in life or an insurance company would underwrite an insurance policy. I believe he would be 96 years old today if he was still alive. I don't want to send information to the insurance company and get screwed out of something if it is fraudulent. They are asking for a death certificate and succession of my grandfather.

FYI, grandfather suffered a stroke in or around the early 1990's and my father became power of attorney over him and he never mentioned this insurance policy.

Any help would be appreciated.