This may or may not sound like a weird question, but given who else is on here, and the minor detail of what this site is, here goes.
We've discussed on here in the past how we as authors can get emotional with our characters, as we're writing the scenes. I had a scene in Love Never Changes where the death of someone made me tear up, and Shaddoth is talking about getting mad at something happening to his character that he, himself, is writing. I get all that.
However, this is a bit odd for me. I'm 6 chapters into a story that quite a bit more graphic sex than anything else I've written. I was in the midst of writing about the main character having sex (a foursome, his girlfriend and her two best friends), and I realized that I was ... um ... aroused. From something I was writing. In my other stories, I've certainly written explicit sex scenes and not had this happen before. (Hell, in one of them, I pulled a video up on one screen, and effectively wrote what was happening on the screen into the story on my other screen (yes, I run multiple screens), as far as who was doing what to which other character and with what body part to which orifice.)