One of our new 4 marcianus is worrying us a bit.

She's the second largest of the 4, so we know she has been eating well. She refused food yesterday and this morning though.
She shed last night, and the shed looks complete, but she does still have a few very small bits of dry old skin (literally just like a couple of small threads of skin in a couple of places).

What's worrying us is that she's making a clicking sound. I've read some old posts about clicking, and there seems to be two opinions - first that it's normal, or second that it's a sign of a resp infection.

I can't see any sign of mucous around her mouth or nose.
The clicking is fairly frequent and not at regular intervals. Sometimes she clicks a twice in succession, other times she goes 15-20 secs without clicking. It's audible from several metres away when she's being held. When she's in the viv you can still hear her clicking if you listen carefully, but it's less regular, maybe every 15-30 secs.
Every time she clicks she moves her mouth slightly, about the distance she does when she flicks her tongue.
The clicks tend to coincide with her breathing, but she doesn't click every time she breathes.
Temps are good (22C cool, 28C warm), she's not in a draft, the tank is dry (aspen substrate), there's some damp moss in one of the hides.
Don't know about humidity as I haven't got round to buying a hygrometer yet, but the house isn't damp and humidity here is about 82% according to the weather forecast.
She doesn't seem bothered by being handled when I took a look at her.

Any advice? Is there anything else we should look for?

Thanks.