My new pet finch is very quiet & keeps her mouth open like shes panting. Should i be worried?

I just bought this new society finch to keep my other company. I brought her home today and she has kept her mouth open all day as though she's panting. She is also very quiet. I've read this just means they are hot but is this dangerous? Should I be worried? I have not seen her drink at all and my other finch who is a slightly larger boy doesn't seem bothered at all. He is much more energetic and sings all day. I'm not experianced with finches at all so I could use some help!