A storm is coming.
Archaeological Resources Protection Act of 2012 is around the corner.
I think there are some of us that venture into grey areas, unknowingly I hope, when it comes to MDing and where we do it at but IMHO if you have a doubt, don't do it!
As far as battle grounds go, many detectorist venture into old battle grounds and pull spent rounds, badges, pins and all types of relics. But the fact is that many battle grounds also second as graves and deserve respect. Sometimes a little bit of knowledge about where your swinging is enough to turn something that's acceptable into something that's wrong.
If you say "A battle happened here, there are many relics out here from that period." hunters grab a machine and start swinging.
If you say "A battle happened here, there are soldiers at rest here." most people remove their hat and offer a moment of silence in respect before moving on.
But with Gettysburg ignorance is no excuse. If anyone is looking for reasons to put an end to this hobby jack@$$'s like that are going to be the one to give it to them.
Or it was a raccoon like mikie said.