You may be onto something, Dee. I experienced what you're going through last year. Autumn hit and for a few weeks, I wanted every carby thing in sight. Fortunately, the cravings went away after a few weeks and I was fine again. This year hasn't been as bad, but I have noticed it again. My DH has been low carbing since the beginning of the year and has mentioned a sudden increase in carb cravings again as have a few of my low carb co-workers, so it doesn't seem to be an isolated thing.
I'll also note that I experienced much the same thing again last spring when the weather got sunnier and warmer again...but again only for a few weeks....Must have something to do with the change of seasons. My personal theory (and this is just a theory, mind you), is that it has something to do with instinct. The days get colder and shorter and our bodies realize that winter is coming and, much like the bear before hibernation, thinks it needs to take advantage of the "days of plenty" to stock up for the lean months ahead. After all, your brain may know that there's a ready supply of food available, but you body doesn't necessarily understand that.