Yep, just me. I was just going to slink away into the corner and hope no one noticed.
I think the mental illness reference is a ... misdirection. People often say "see ya later", or "good talking to you", or "I hear you", in emails and letters, without being accused of being disrespectful to those that a blind, dumb or deaf.
Perhaps there are writers than seem to hear audible voices, but that's not my usual interpretation when I read of writers "hearing voices". I read that as a figure of speech, or a shortened form of "it is like I have heard the voices in my head". Perhaps I am content to interpret it that way because that is the way it seems to me.
And, yes, it often does feel like it came from somewhere else. The image or the words sometimes seem to appear in my mind like a memory of an experience or hearing someone speak. (Or, as I suggested in my first post, very much like reading a good book where everything seems very real.) It was a vivid "memory" like this that drove my first published novel - the story that evolved into a trilogy all came (eventually) as an explanation for the opening scene (the start of chapter 1, not the prologue).
But, however it may feel at the time, I am not of a mystic inclination, so I have other explanations. Most of the time I can feel quite certain that these false flashes of memory (and I recognise them as false) come from spending so much time immersing myself in the characters and scenes that I can reasonably justify them as the work of my subconscious mind. A few (like the scene alluded to above) are less easily explained, but daydreams and waking dreams are not uncommon experiences and need no mystical explanations.