Does a change in altitude affect baking time or temperature?
Usually this question goes the other way around (how to adjust recipes for high-altitude cooking)...

The main effect that altitude has on cooking times and temperatures is how it affects the boiling point of water. At higher altitudes, water begins boiling at a lower temperature, so anything boiling will not reach as high of a temperature, and often needs to be cooked longer.

Higher altitudes can also cause leavening to have a greater effect. You may need to add extra leavening (yeast, baking powder) to get the same amount of rise that you had at a higher altitude.