Changing temperatures and the duration of the bake will certainly affect the loaf that's in the oven. Normally I preheat the oven for 20 minutes at 475. I bake under a cover for the first 15 minutes at 475, take the cover off and lower the temperature to 425 and bake for 30 minutes.
This time I have preheated the oven for 30 minutes at 475, baked under a cover for 15 minutes. Then I removed the cover and baked at 400 for 30 minutes. The loaf looks great.