Grey American green tree frog?

[kueluck]

My male stays on the darker side, more browns, some times even black with slight lines of green on his legs.

[aegillesp]

The odd thing is, he was brown at the store and in the container I brought him home in. He just stays grey. My other male turns the same green color as my females when he is awake but is brown when he sleeps. It's sooo weird!!