I asked my bank about that. They said that while tellers usually ask for a signature, people can avoid that by depositing the check in an ATM. The bank will usually then just process the check. My local bank, on which the check was written, told me that since it already cleared, there is no recourse. But I haven't checked with the RI bank. Someone else posted on an eBay forum that the most the other banks will do is to tell you whether that person's account is still active.

My bank manager also said that if they have my bank account number and signature and start cashing fake checks, then that is considered forgery for which my bank has insurance, so I wouldn't be out any money. Odd that a fake signature would be covered, but the lack of a signature would not be. I guess it's the difference between the person writing and the person cashing the check.