My smaller star which is a couple of months old has been very lathargic the past 4-5 hours. usually when I pick it up when it's asleep in the afternoon, it would open it's eyes after a minute but this time it is taking much longer. This morning it was fine and very active but the past few hours he has been very lathargic and refusing to eat. No running nose and clear eyes, everything else being the same. Is this their normal behaviour once in a while? The weather has been cooler these past few days but still over 25 degrees celcius.