I had noticed this in one frog. He appears to be healthy, having interest in food, going in his little hide-outs, and camouflaging himself in the silk plants.
I figured he must have ate a little too much and didn't have room in his stomach, but I just want to make sure this isn't a concern.
I hand feed him, which really means chasing him around the tank until he realizes I've got something he wants in between my fingers, but does readily gobble it up.
This is the first time I've seen this behavior so maybe I over-fed him a bit?