I have been selling my items through Nook's Cranny, however, noticed something: the prices of the item I am selling usually increases/decreases during a certain time. For instance, I was selling a Gigas Giant Clam at around 3 a.m. where the price was 12,000 Bells, then when I sold another at around 8 a.m, the price increased to 15,000 Bells. Any idea why?