hives build false cell cups all the time, some hives more than others, the thing is to look in the cell and see if there is a larva, if not then just tear it down yourself, its a good practice to use that way you not having to look in 30 of then during inspection.
I thought our flow was over also about 3-4 weeks ago, looking the other day and they have frames of uncapped nectar, dont know where its coming from but saves that much with less feeding..