Scaly leg mites are microscopic. You will not see them on examination. They are like a mange. They burrow under the skin between the scales and spend almost their entire life on the bird. Dusts and powders don't do much--you have to treat the bird.
Yes, I believe the pics show what could be a very early stage case of mites. There are some sprays you can use, but you need to apply them often and make sure it gets under the scales. Additionally, you can apply something like Bag Balm to the legs to smother the mites but it needs to be done thoroughly and frequently to be effective.
I have one hen with a really bad case that I've been battling for about a year at least. My other birds seem to be more resistant as only a couple have a few lifting scales. I've begun to use fipronil on her out of desperation. It is helping and her legs look much better after 3 months. I'm also doing monthly leg soaks and scrubs to remove the old scales and applying Bag Balm to her legs. Scaly leg mites can also be treated with ivermectin injections, but I'd need to find a vet that treats chickens. I may eventually go that route.
If I were you, I'd treat it as if it were leg mites. Leg mites are a pain in the butt and if left untreated can cripple a bird so it's better to be safe than sorry. Soak, scrub, spray, and grease up their legs. Do it again in 1 week, then twice more at 2 week intervals. Clean and dispose of all bedding in the nest boxes (because birds spend a lot of time in there it could harbor mites) and spray well with a miticide. Paint the nest boxes if they are a porous surface to make subsequent cleaning easier. Clean nest boxes in this manner frequently and at least every time you treat the birds legs.
I think I'll treat them with a spray just in case - I suppose you can never be too careful! I did a major clean out of the coop the other day with all sorts of organic mite killing sprays and dusted them all thorougly with DE so hopefully that will have done something. 
