I would wait and see. I doubt it's lice of mites at this age and with no exposure to adult birds (or wild birds). I have only recently recalled the problems I had with lice when I was young. I haven't seen lice on the farm at all and I think it might be because all the chickens dust bathe freely on the farm.
Lice will show up first around the vent and later under their wings and on their heads. Just check their vents from time to time and you'll recognize a problem because you know what normal look like.
my chickens are almost one year old..................maybe 9 months...............
One chicken is 1.5 yrs old...............
I will check the vents etc.............just wasn't sure if you were thinking mine were younger?
Quite possible if they have been outside. Look for moving bugs. They are tiny & depending on what kind, may be black, brown, red or sandy colored. If it moves, it's a bug. Treat it if it moves.