I'd ask the manufacturer.
Note that the smaller the delta T (difference in temperature) between outside nd inside, the smaller the heat loss and therefore the size of furnace required to keep the house at the desired set point. So, the colder you keep the house, the smaller the furnace required, even for the same house. A furnace would not need to run as long if it was sized for a higher temperature, and short cycles are less efficient. Just like running your car around town on numerous short trips when it doesn't have time to fully warm up. So, depending on how much oversized the furnace really is, it might be an issue. Now, if it was sized for that temperature, it would likely be little different than one sized for the higher temp.