Very interesting thread this, Tone. This is not a Uriah Heep (the Charles Dickens character, not the 70's rock band) kind of sycophancy, just a statement of supposition, but I would guess its just you getting your songwriting hat on and simply being really good at your 'job', the same way other people go in to work in the morning and do theirs.
I feel now that after having been composing tunes for (what seems like) a very long time and having become very self aware of my own process (and also having become familiar with certain other people's creative processes too), I think I am pretty much aware of how it works... it only takes me by surprise every now and again, when I come up with a structure or progression that didn't seem to be a familiar part of my usual armory. I think we all have subconscious patterns that we develop over time, and inspirations and influences can play a bigger part than we sometimes give credit to, but there are definitely certain characteristics that people develop. Of course there are natural geniuses out there but the greater majority of us have to hone our skills... so don't be too surprised (or modest!) if something that is a major part of your life reaches a personal peak of artistic achievement. You are doing something you love to do, and you've obviously gotten pretty damn good at it.