My guess is that it's from her meals- maybe you just didn't notice at the time? OR, she has swallowed some indigestible bits of course substrate (wood chips, bits of branch?) and in passing that, it irritated her cloaca- that could have resulted in the smear, though maybe not the tiny specks. The smear might also have been her sliding over a droplet (from her prey) after she ate.
73* is rather low for ambient temp, btw.