When you live in a secondary or tertiary city and need to travel to another one in another region, there are many such flight combinations, sadly. Delta often only serves these cities from their regionally located hubs, meaning if you need to go from a smallish city in the west to a smallish city in the east, you are often forced to jump through both SLC and DTW, for instance. It also happens pretty frequently when service is infrequent on a one-stop itinerary between city pairs and then the flights get retimed seasonally, sounds like is what happened here.

I also doubt the ticket is full F. It's probably paid F, the discrepancy of which is lost on many.