Mites?? Whaaa?

[Javen]

Ok, the first time I saw one of these buggers was in my beardie's tank. It wasn't on him, but just meandering about the top of the substrate. Much much too small to be a cricket, that's for sure. But it does seem to be the size of one of their eggs, I think.
I plucked it out and studied it so that I could check online to see what it might be, then drowned it.
I scoured the rest of his cage and found nothing, checked every inch of him (much to his chagrin) and delved into my snakes' habitats as well. Nothing... neither in the substrate or actually on the animals.
So I let it go for several months... without another sighting.
Just today one of our mice got loose and I was laughing much of the morning watching John try to catch it. (Literally, a bull in a china shop. John's 6'9", trying to catch a hopper about the size of half his pinky finger in a room full of cages and potted plants. Let's just say I had to break out the vacuum cleaner)...
Anyway, once the lil troublemaker was caught in a container, I glanced inside after dumping him in with the rest of his family.
There in the corner of the container was another one of those bugs! I couldn't tell if it had come from the mouse, which I doubt since I've never seen one in their cage either and he'd only spent a few seconds in the container.

So... I finally went online to see what I could find. Any type of mite picture I could dig up for both reptiles and rodents looked quite similar to eachother: a ticklike, dark critter with what looks like a single segment. Which isn't anything like this type of insect, which is a two-segmented animal with a light yellow, almost translucent body.

So I started looking up aphids. MUCH closer but not quite. And none of my plants seemed infected.

Does anyone have any idea what these things are? I tried to take a picture but it was too small to pick up with my camera....

Thanks for any help.