Gettin' kinda worried

[Teh Frog Whisperer]

I've had my White's tree frogs, Fremont and Rio, since Monday. Now, I have handled them a few times, and when I do I notice a reddish-orangey coloration on their belly skin. To me this screams either IRRITATION or BACTERIAL INFECTION. They both seem healthy and it looks like they spent the night pigging out on the crickets I put in there. Also, Rio tends to turn a brownish color at night, then back to his happy light green in the morning, which kinda makes me confused and a bit more worried. Can someone help me out here? These are my first tree frogs, so I'm just not really knowledgeable about them and stuff.

[Sasha]

I don't know about the red/orange color on the belly but I can tell you that my Shrek spends most of his time brown. In the morning he is a yellow/green color for about an hour, then once he goes back to sleep he is brown again. Where his sister Fiona is a very pretty lime green color all the time. It's almost like a mood thing for Shrek, he's not very social and prefers to just sit and hang out on his stump, where Fiona is very active and curious.