Several years ago I was talking to a dynamic young student journalist who had this incredibly annoying habit of referring to everyone on her school paper's staff as "my reporters," "my copyeditors" or "my photographers." It was the "my" thing that really grated on my nerves.
I doubt she even realized she was saying this, but I found it patronizing and a not-so-subtle play for power.
The reason I bring this up is that on some of the freelance forums to which I subscribe, there are freelancers who describe "my editor" at various national pubs as if they worked with them exclusively. I see it as their not-so-subtle way of grabbing for power when in reality freelancers have little power in that relationship.
Having spent nine years of my life as a magazine editor working with freelancers, I am keenly aware that the power lies with the editor. If someone was a pain the neck, I just didn't hire them again.
Bearing that lopsided dynamic in mind, I prefer to refer to a magazine editor as "the editor I've worked with" as opposed to "my editor."
The exception to this rule is if you are on staff or have an ongoing contractual arrangement with a specific editor — as in "my" book editor.