This is an interesting find. Perhaps astronomers need a little sign on the telescope that says: "Caution: objects in universe may be closer than they appear." But I guess that's a little optimistic.

Another though experiment. Let's say gravity (which is variable) also affects time. Thus the progression of time, as constant as it appears to us, is actually quite variable as well. Since speed is distance divided by time... That would mean the speed of light would actually vary depending on the influence of gravitational fields. However if you went from one gravitational field to another, the influence of the change in variable time would be such that you'd observe the speed of light being the same in different locations despite the fact light is actually changing speed as it goes from one location to another. So the speed of light may be more of a universal coefficient type thing than a universal constant type thing.

I wonder if some physicists would hate a layman like me for bringing up an idea like this. (But then again, perhaps that's what the significance of this observation is about.)