Something missing in ammo charge

I'm talking about the story that appeared Feb. 3 about the owner of Slumasters in Braceville being charged in federal court with selling ammunition to a convicted felon.

The story says Nancy Hagmaier sold the ammunition to an unnamed felon in June. She sold the felon 150 rounds of 38-caliber ammunition.

The charges apparently came after a "lengthy investigation."

Here is the part I don't get. How would someone know whether or not he or she is selling ammunition to a felon? The last box of ammo I bought didn't require me to show any kind of ID or database background check. Perhaps the law has changed, but I'm not aware if it has.

I know background checks are required to purchase a firearm, but ammo?

It will be interesting to follow this story as more information is learned.