I don't think you will find anyone is coming to look for it. As I stated earlier, it seems this happened a lot. If it had not happened there would be far fewer M1911's and M1911A1's in personal collections these days.
I own a Colt M1911 of 1918 vintage I purchased several years ago. It was even processed through the Federal NICS. It also had to of been one of those misappropriated from the U.S. Government as some point in time.
So in different eyes, grandpa(s) was either a villian or a hero for stealing a Government pistol(s).
The only people in jeopardy is possibly someone with one of these pistols with an eradicated serial number or inappropriately altered serial number.