Glad Nim ate!
I have not had to deal with mites. I know many who have and I'll throw in my two cents but hope others fill in the blanks or correct me if I am off base.
I would let Nim digest and see if there is any other evidence of mites. Looks like you are using paper towels as substrate and that should show mites well. You might want to switch to a white water bowl, but you should be able to see mites with the paper towels underneath.
There are other insects that could find their way into Nim's enclosure. If you only saw one it is possible that it was not a mite. I am not saying there aren't mites but you want to be sure before treating.
Treatment can be rough even if necessary if mites are present. You want to be sure that is what you are dealing with before treatment. You also want to look into treatment options.
What were you thinking you would use if Nim has mites?
I hope others chime in here and talk about the best mite treatment options.
The most important things are to let Nim digest fully, make sure you are dealing with mites, and find the best and safest treatment option(s).
Good luck and keep us posted.