Difficult Neighbor (A Memory)

I'm glad this is all in the past. But I've been thinking a lot about it lately.

I was living at an apartment, an end unit in a row of six. There were six more in the other building on the other side of a grove of olive trees, a swimming pool, and a utility room. There was a new neighbor next door, on the other side of the shared wall from me, some guy who came and went at odd hours. He was a little rough around the edges, but not noisy.
So one Sunday afternoon, the boys (they were about 7 or 8 then) and I were playing around in the living room, laughing and having fun, but I guess being kinda loud. In the midst of our raucousness, a shadow formed over the screen doorway, and a booming voice filled the room: "Keep it Down!"
I was terrified, and I'm sure the boys were too. He went back to his apartment without saying more, and I don't remember if I said anything to him, maybe something like "hey, it's Sunday afternoon" or something like that.
I thought he was pretty scary and out of line, and I called the cops.
When they came I told them our story, and then he went next door to speak to my neighbor. Since the walls were thin, I tried to listen to what they were saying over there. I heard something about a DOC number. DOC. What the heck is that. OH MY GAWD. Department of Corrections. The guy is an ex-con. Jeezus. Now what have I done. Then I got Really Scared.
The cop came back and told me how it went, that the guy is a nurse and works odd shifts and had been trying to sleep. He didn't actually pass along an apology though, but it was an almost one. He said he knew he shouldn't have yelled into my doorway.
After that I vowed to buy a house, to move out of those apartments.
It turned out alright with that guy after that, though. About a week later I met up with him going to the mailbox, and we talked about the incident. Then later on I saw him out in his patio adjacent to mine, and we talked about the strawberry plants he was growing, and then another time he showed me the injured bird he was taking care of. A regular Birdman of Alcatraz right next door!
After moving to the house, I saw him a couple times in the neighborhood, and we were kinda friendly.
I never found out why he had been incarcerated.