A: No it is not. It sounds like your Heat Banks (strip heaters, auxiliary heat) are not working properly. On cold days, like we are having right now, a Heat Pump can't keep up by itself, So it has a set of Heat Banks to assist (similar to the old electric wall heaters) inside the unit. Heat Pumps generate heat roughly 40 to 55 degrees over outside temperature, so if the outside temperature is 10 degrees the Heat Pump alone will generate heat at around 50 to 65 degrees by itself. That's a little cool, so the heat banks kick in to assist in maintaining temperature inside. We get quite a few calls at the Service Center asking about the Auxiliary Heat indicator (AUX) flashing on the thermostat, in these temperatures its perfectly normal. Yes, it costs more to operate but that's simply because its very cold. However, if the Heat Banks are not working properly, your Heat Pump will not not be able to keep up and you will be uncomfortable. I would advise you to call your Heat & Air Contractor for a service call. Be Comfortable!