You are yourself a hobbyist, and you enter this brand-new bill, only to find out that it’s already been entered.
I’ve hit perhaps one such bill, maybe two.
Never heard the term “sherlocked” until today though!
I have, several times, made origami of dollar bills and left them out somewhere. 2 of the three I did this with have turned up 
The way I understand it, the problem the Secret Service had with Hank was that at the time he was also selling the WG rubber stamps at his site. That made the markings on the bills advertising, which is a no-no. He agreed to stop selling the stamps and now everything is hunky dory as long as you don’t mess with security features, serial numbers etc.
I’d heard that as well.
However - there appears to be nothing to stop OTHER places from selling such stamps - a lot of stampmaking places online carry them. I bought one from such a vendor.