With your driving patterns and this being winter, that mileage is to be expected. Take it for a long 200 mile drive on highway and keep it under 70 mph. Fill the tank just before the trip and then top it off at the end of the 200 miles and do the computation. If you get low twenties, then you definitely have a problem. But if you get high twenties or barely thirties, then your car is running in perfect shape. I suspect you will be pleasantly surprised.
I typically lose 1-1.5 MPG in winter -- on every vehicle in the past several years. That's mixed-city driving. We pretty much have E10 everywhere -- even though they do not have to tell you (I hate that!). At least in IA, you know what you're getting.