Not a problem, just an occasional occurrence with these frogs. Sometimes (Especially in adults) they will become lazier than their usual limited activity and even will just open their mouths and expect you to just place food in. Sometimes its when they're between growth spurts and sometimes the adults will just eat have less of an appetite. They will do this off and on. Seasonal changes detected by the frog can also make them a little lazier than usual. Its when they suddenly refuse to eat at all when you need to begin to worry. Loss of appetite and weight loss are definite signs of a problem.

You could skip a feeding and raise the temps a little higher for a couple days to increase their appetite. 84° Should help boost their response. Keep humidity high as well.