Looks cool, I've always wanted one. As for the mite/spiderling I don't know, keep a close eye on him and keep him away from your other herps incase it is mites. Hopefully that is not the case, My skink had mites and they were a pain to be rid of.
It may be a mite, but I'm pretty sure it's not a reptile mite. The guy had just ate a wolf spider carrying an egg sac so I thought it might have been a baby spider.
If you can confim it's a reptile mite tell me though.