State of Maryland rebate program going door to door ?

So some idiot in our apartment complex didn't lock the front door. I end up getting a weird knock on the door by a guy who's going around to all of the row homes trying to walk in and knock on doors of apartments . He said he was part of the 'State of Maryland Rebate program'. I snuck up to the door and looked through the peep hole. The guy had a clipboard and what looked like a ID of some sort hanging around his neck. I of course never opened the door, but he walked away and said 'ok no checks for you'.

Is this some sort of scam or someone trying to break in? I've lived here for years and have gotten 0 knocks on the door other than expected guests. And working on a Saturday using a vague title like the State of Maryland Rebate program'?