Excessive water on upstairs flooring plywood

There were a couple of patches of water on the upstairs flooring plywood that made use think there might have been a leak in the roof because the windows were closed and even if the windows were open, it'd take one mighty storm coming from the wrong direction to get that much water where it was.

This was explained away as the plumber having caused it (and knew about it so where was the towel to at least sop some of it up, eh?) and subsequent storms have resulted in no undesirable water accumulating inside the house even with the windows open.