Yes, the grass never really dried out all day, did it? At 6:00, I was still seeing wet on my boots, still getting wet from rubbing against a tree. The heavy clouds, no sun, not much breeze, ... kept the humidity high, and nothing dried off much.
I was surprised that mowing worked as well as it did. I suppose it speaks to the lesser growth than a couple of weeks ago, and the water content of the grass blades is much less too.