So, I was just assaulted by a trio of fairly well armed thugs while walking out of Riften. Before attacking me, they informed me that they were 'here to teach me a lesson.'
After dispatching them in due course, I found this on the body of what I can only assume to be the leader, given his vastly superior armaments:
Orgnar is the innkeeper in Riverwood. Now, I admit, I've stolen a fair amount, but I pride myself on having never been caught. My total bounty to date is at zero. So, how did he figure out that I stole something, why is he taking the law into his own hands, and if I go back to Riverwood, am I going to get shanked?