You didn't note the 10 degree drop in temperature around Kyneton (though guessing you left Bendigo earlier than us). I always joke it gets sunny north of Macedon, today it was definitely true.
Being a veteran of the Calder trip, I think there are two meterological divides. The cloud often ends around where the divide crosses the Calder. But in winter the temperature change is often around Taradale.
The unusual thing about yesterday for me was that the cloud boundary was around Gisborne, and was very low, even with a bit of fog on the south side of Gisborne. As Neil says, it's usually further north; indicates how shallow the change was, at least initially.