I'd call this something a bit more serious than odd. Sounds more like a dry run for something bigger.
Nah Wasp, I see a very simple explanation for all this activity.
We have a huge population of people that live down under in our major city's. A huge city of the homeless and they have learned to tap into the creature comforts of top side.
Quite amazing what they do to live down there and how they can set things up for all the comforts of home. Seen a couple of films on the History Station on this sub world we seldom have any idea exists.
The only thing the people need is food and they raid the dumpsters for day old bread or vegetables that are ok to eat. Rest.. by law must throw out any prepared but uneaten food each night as do grocery stores that dump out of date canned goods.
My thinking is this eating establishment put a lock on their dumpster, a once prime picking place for food.
Saw this in VA when the fast food paces were ordered to pour bleach in the dumpsters so the homeless would not become ill from food only 2 hours old.