City Notice? Scam?

I came home to a fluorescent green door hanger informing me that I had 48 hours to remedy my "refuse bin left in public view" (and citing city ordinances). Is this for real? I don't have a neighborhood association or HOA. Furthermore, I was literally out there when the truck went by and retrieved my bin within a minute of pickup, so I'm…really confused, since the note was therefore left after I had already moved my bin back into my garage. It had the real name of a city official (and their real phone number), which I called to inquire, but got no response.

If legit, the only thing I can think of is that a neighbor left theirs (it's a shared driveway situation)- but the curb was empty of bins the morning after pickup, which is a perfectly reasonable window of time for retrieval, given time of pickup and work schedules.

Anyway: anyone deal with this before? Is this something the city actually does? Is it a scam? Also, what the f**k does 'in public view' even mean, when most of the houses store their bins (neatly) at the head of their driveway and they didn't get notices?