I don't think it's anything to worry about. Looks like Derp is a female. Female ACFs are identified by a swollen cloaca (vent) and the lack of nuptial pads (they look like black gloves on the frog's long fingers). Also, it is worth noting that female ACFs also call.

Although, I haven't seen a cloaca that large on such a small frog. It should be watched and if there is any significant changes, please post the pictures,