I agree with Kurt, check all the care sheet requirements and make sure they're being met. After that if there's still a problem I would check the frogs for any physical ailments on their skin or eyes, if there's nothing there, you should be fine.

If you do see some eye or skin abnormalities it's time to post pictures here and ask for advice and/or take the frogs to the vet. Nothing that serious yet though, it sounds like so don't panic. I'm sure they'll be fine as long as their temp and humidity requirements are met.