I'd think if it was a monster buck I'd make some calls and figure out the legality of it but I think your safe. I know the DNR around the surrounding counties of Chicago really doesn't care too much, I tried to call it in once and they could have cared less. I think if every head was called in that was found while shed hunting every year, the DNR would spend more time trying to get tags out then to concentrate on other more important things.
I wonder where do you draw the line? If I find a 6 inch spike do I have to call it in like I would a 150 inch buck? I can understand if you find a monster buck but if I finds a decomposed 6 point do I call it in? I think it's a judgement call, at least in my opinion.