When you get a chance, really look them over good for lice/mites, look for white powdery looking qtip like buds at the base of the feathers as well - that would be lice eggs.
Again, when you can give them a bit more straw to help keep feet from getting soiled, but change it all out frequently. While SLM do mainly live on the bird underneath the scales of the legs/feet, they do migrate (slowly) so it's possible your other birds could get them.
Getting a fecal float to check for worms would be good too, if not then I would consider worming them.
Keep watch on behavior and droppings. While they are old enough that they should have resistance to the strain(s) of Coccidia that was in the environment they came from, you may have different strain(s) that they have not encountered. Just something to keep in mind.
