Is there something wrong with my frog?

Question
I have a White's tree frog and she usually spends most of the day hiding behind the leaves, up on the back but today I looked in her terrarium, and she was hiding under the bark and moss and all that was visible of her was a small amount of her back because some of the moss fell off her.  Is there something wrong that would make her want to hide?  I just changed the bark and moss in her tank, but everything is in the same place.

Answer
Dear Avalon,
thank you for your question.
I don't think that you need to worry. Make sure the humidity is high enough, if it's too dry she may choose to bury herself to keep moist. But I think that she just chose another hiding spot for herself.
I hope I was of some help to you
Jennifer