I had Federal do the same thing a few years back.
Like you, I was duck hunting. When picking up my empties at the end of the day, I noticed that a lot of the crimps were blown off and the remaining edge looked sort of singed/melted. They fired fine, killed ducks, and didn't seem much different while shooting them.
Regardless, I called Federal, just to pass it along. They asked if I'd send them a few to inspect, which I did. A couple weeks later, I got a couple boxes sent to me, out of the blue!
It wasn't expected, but certainly appreciated!
